The Tip Top pegmatite
A Historical Review and Mineralogical Update

by Thomas A. Loomis & Thomas J. Campbell
from MATRIX Vol. 10, No. 3 Issue

Most mineral collectors have their favorite localities. For shear beauty and perfection, Tsumeb, Mapimi, and Pala have little competition. For species number of species, Långban, Mont St. Hilaire, and Franklin are in a class of their own. It is truly a natural wonder when a single deposit through the virtue of geological conditions can manifest creation of such spectacular crystals as blue cap tourmalines or delicate, aqua-blue sprays of aurichalicite. How this same set of conditions can be duplicated thousands of miles apart is even more amazing. However, a truly unique deposit has no equal. The same geological conditions are rarely repeated elsewhere in the world. To the species collector, this is tantamount to the definition of rare. At the Tip Top mine, near Custer South Dakota, the alteration of beryl and triphylite has created the minerals ehrleite, fransoletite, pahasapaite, parafransoletite and tiptopite.  These minerals are unique to the Tip Top mine, and this unique assemblage of beryllophosphates have yet to be found elsewhere in the world. The Tip Top mine is the type locality for twelve minerals and host to at least sixty-four confirmed phosphate minerals. 

Tom Loomis with Dr. Buford Nichols at the Tip Top mine in July, 2002

Though the Tip Top mine is not central to part of the colorful mining history if the Black Hills, the mine is undeniably an icon of Black Hills mineralogy.  Like so many of the mines in the Black Hills, the Tip Top has its roots in the tin mining days of the 1880’s. But it would take an entire century for the Tip Top to expose its treasures. T. J. Campbell and W. L. Roberts would then introduce the minerals of the Tip Top mine to the world in a 1986 issue of the Mineralogical Record. Since then a few more discoveries have been made. Several well-known mineralogists, geologists and few local miners were involved with these efforts.  This article is intended to bring the reader up to date on the mineralogy, while adding some of the untold “behind the scene” stories to the history of this great locality. 

History 

Although the Hill City pegmatites received much early attention in the central Black Hills because of the “tin boom”, most the pegmatites around the town of Custer were originally located for mica. The Tip Top mine, located about five miles southwest of Custer, was unusual in that it was staked as a tin prospect sometime in the late 1880’s by the Nevin family.  Few other mines in the area were staked for tin. Fisher (1942), however, states that Nevin mined mica hoping to find tin. Through its history, the mine produced little, if any tin.  In fact, it is extremely difficult if not impossible to find cassiterite, the primary tin ore, in-situ or in the dumps at the Tip Top. As a result, and for lack of any other economic mineral, the mine sat idle until 1925 according to Fisher (1942). At this time, Nevin attempted to market phosphate rock for its lithium content. This attempt was unsuccessful. In all likelihood, the triphylite (lithiophilite, in Fisher) was too lithium poor while other pegmatites in the area contained higher-grade lithium minerals such as spodumene, amblygonite and lepidolite.  

With the greater demand for feldspar in the world economy, the Black Hills experienced a surge in feldspar production starting in 1923 and an even greater surge starting in 1935 (Page et al, 1953). At this time, the Tip Top found new life as a feldspar producer. The feldspar mining created a fair sized open-pit during the early 1940’s with dimensions of 150 by 50 feet to a depth of 40 feet.  The International Mineral and Chemical Company leased the mine during the 1950’s and 60’s and produced large amounts of potash feldspar (microcline perthite) along with beryl, montebrasite - amblygonite, spodumene and columbite-tantalite as byproducts (Campbell and Roberts, 1986). Mica mining also resulted in a few small pits north of the feldspar pit (Page et al, 1953). These small pits are still evident today. The mine was essentially inactive during the 1970’s. A local miner, Vern Stratton of Custer, deepened the pit significantly by mining beryl in the early 1980’s. 

Geology

 According to Campbell (1984) the Tip Top is a pegmatite of intermediate depth of formation (3.5 to 7km), based on Ginsberg’s classification, and is enriched in Be, Li, Rb, Cs, and Ta-Nb. It is also spatially and temporally related to the emplacement of the 1.8 billion year old Harney Peak Granite that forms the core of the Black Hills. Fisher, on assignment by the State Geologist, Dr. E. P. Rothrock, in 1942 was the first to describe the geology of the Tip Top mine for economic considerations.  Norton and Stoll, as part of the Strategic Minerals Investigations also described the Tip Top in September of 1942 and August of 1943, respectively (Page et al, 1953). Fisher chose the Tip Top, along with two other mines, since it as a whole represented the general geological character of most pegmatites in the Custer area. The Tip Top mine is a classically zoned pegmatite comprised of distinct mineralogical shells or assemblages. Campbell (1984) described four zones from wall to core: 

1. Perthite-quartz-biotite zone (wall zone)
2. Perthite-quartz-muscovite (outer intermediate zone)
3. Perthite-quartz-muscovite-triphylite (inner intermediate zone)
4. Quartz-montebrasite-spodumene zone (core zone)

Pale to deep flesh-colored perthite microcline is the dominant mineral overall, especially in the intermediate zones, with quartz being the next abundant mineral. Late stage fracture fillings and/or replacement bodies of quartz-albite-muscovite+/-microcline are evident, which were responsible for replacement textures associated with some of the hydrothermal alteration. Beryl mineralization is associated with these fracture fillings and replacement bodies according to Fisher (1942). The beryl crystals, within these fracture-filling units, are light greenish yellow and commonly occur as large, skeletal crystals from a few centimeters up to several tens of centimeters. The core, or “hoppered” portions, of these crystals exhibit intergrowths with microcline, albite, quartz, and muscovite. The only pure beryl crystals are not over a few centimeters in size. The large beryl crystals evidently grew faster on the extremities relative to the inside. As Fisher states in his own words: 

“…the beryl had great crystallizing power. It grew, engulfing everything in its way, though at somewhat different rates. Like the German tank battle against the French in May, 1940, it first surrounded and then assimilated or liquidated.” 

Fisher (1942) described the pegmatite as being “crescentic” in shape and about 200 feet wide at the center. The largest part of the pegmatite, according to Fisher, was the intersecting “portions” of the pegmatite, which caused a bulge along the footwall on the northeast side.  Fisher further describes the geometry as resembling a rain gutter with the edges being thin and the center the thickest. The whole of the pegmatite is 1000 feet across and dipping 40 degrees to the southwest. Fisher does not attempt to zone the pegmatite but states that steeply dipping joints and faults caused a pronounced sheeted structure.   

Fisher’s early predictions in the 1940’s suggested, at that time, that the pegmatite continued with depth.  Fisher further states the trough of the pegmatite may thicken and “possibly widen with depth presumably for only a relatively short distance”. Fisher was certainly correct at the time due to the fact that the pit was about 40 feet deep in 1942 and by 1982 the depth had increased to about 125 feet.  Therefore, another 85 feet in depth had been realized and Fisher’s theory proved out. There has been speculation since the1982 mining activity and mineral discoveries that the pegmatite continues at depth. This is, in fact, very plausible considering that pegmatite was still exposed at the bottom of the pit after mining was terminated after 1982.  

Mineral History 

It is generally thought that most minerals from the Tip Top were discovered during the 1980’s. However, there were earlier signs that the mine would reach scientific stature. In the 1940’s and 50’s many notable geologists such as Cameron, Hurlbut, and Jahns studied pegmatites in the United States. Out of these years, many classical works would be published, such as Henry Jahns’ paper “The Internal Structure of Pegmatites” published as part of Economic Geology’s 50^th Anniversary. Later in 1964, Bill Roberts with George Rapp Jr. published the “Mineralogy of the Black Hills”.  Both Jahns and Roberts were well known in their fields and contributed tremendously to the mineralogy of the Black Hills pegmatites. Paul Moore, an expert in phosphate mineralogy from the University of Chicago, was in the Black Hills studying over100 pegmatites with Bill Roberts in the early 1960’s.  It was only fitting that Moore would name two newly discovered minerals from the Tip Top mine after these men. Moore with Roberts, would find a third mineral, and name it after Curt Segeler, a well-known mineralogist from New York. The three new minerals, Robertsite, Jahnsite and Segelerite were the first of a suite of new minerals to be discovered at the Tip Top mine.  Moore would later publish his findings in the American Mineralogist in 1974 and would have this to say about the new discovery at the Tip Top: 

“Rarely does an investigator in descriptive mineralogy have an opportunity to announce three species new to scientific intelligence which not only occur intimately associated but appear as well-developed crystals”. 

“….these crude giant crystals of triphylite suffered extensive retrograde oxidative and metasomatic reactions…..Vuggy cavities in these phases contain a host of late stage hydrated transition metal phosphates…… . Phases discovered in these cavities include leucophosphite, as lovely greenish-grey, purplish-pink to deep amethystine prismatic crystals: hureaulite, as pale yellow, to pale pink to red-brown prismatic crystals; collinsite, as colorless to white radiating sprays, lath-like crystals, and flattened chisel-like rosettes; hydroxlapatite, as rounded colorless hexagonal prisms, whitlockite, as colorless simple rhombohedra; bermanite, as deep reddish-brown druses of thin tabular crystals; laueite, as striated orange laths; mitridatite, as thin brittle greenish-brown plates and olive-green stains; and the new species jahnsite, segelerite, and robertsite”.

Hureaulite to 1.5cm, Tip Top mine.
Tom Loomis specimen and photo

Jahnsite on Rockbridgeite (black) to 0.5mm oh Leucophosphite,
Tip Top mine.
Tom Loomis specimen and photo

During the same year, Roberts et al (1974) would publish the classic work Encyclopedia of Minerals and described many of these same phosphates with many color microphotographs taken by JuliusWeber and Lou Perloff. It was obvious that the micro minerals of the Tip Top mine were becoming internationally known. This was just the beginning. 

The dumps of the Tip Top mine in the 1970’s would yield several species of rare phosphates from triphylite alteration assemblages. But if it weren’t for the efforts of one man, Vern Stratton, the Tip Top mine would have slipped away as just another interesting phosphate deposit.  Stratton mined the Tip Top for beryl and feldspar from 1981 through 1982. It was during these years that the rare beryllophosphates to which the Tip Top mine is now known for were discovered. At this time mineral collecting in the Black Hills may have been at its height. The School of Mines was enjoying peak student numbers pursuing geology and mining degrees and mineral collecting at the abandoned pegmatites was popular. Bill Roberts was teaching “Min. & Crys.” and one of the authors (Tom Campbell) was a graduate student.  June Zeitner, the “Queen of Mineralogy”, as she is today was active in mineralogy and living in Rapid City. Bob Farrar along with Pete and Neal Larsen of the Black Hills Institute of Geological Research would also play vital roles in shaping the Hills mineral history. Icons of geology such as Jack Redden and Alvis Lisenbee were teaching structural geology and optical mineralogy.

Stratton, mining on the lower levels of the mine eventually blasted into an area of altered beryl. It was this area that yielded beryllophosphates yet never seen before by the scientific community. Beryl specimens full of phosphates were quickly distributed to the priority collectors, who seemed to be at the mine for each of Stratton’s blasts. Bud Ehrle during a recent conversation described how he found the type specimen of Ehrleite. 

One day while walking around the recent mine workings I checked out a 55-gallon drum filled with beryl that was soon to be shipped to the beryllium buyer in Utah.  I noticed some small white crystals on some of the surfaces and was able to keep a specimen to be analyzed later. It turned out to be an unknown, never before described in mineralogy. We never found anymore of this material. This specimen now resides at the Canadian Museum of Nature and is one of only three matrix specimens of erhleite.  The other two are at the South Dakota School of Mines and the National Museum of Natural History in Washington.  The rest of that barrel and the rare phosphates that must have lined hundreds of cracks, were reduced to dust at the processing plant soon afterward. 

Another story involved Bill Roberts. Like most big finds, specimen acquisition and keeping the crowds out was a little hard to control. Bill as it turned out was getting a little to “anxious” at the peak of things. Tom Campbell recalls this moment during these times. 

Excitement was high during the course of the renewed mining at the Tip Top due to the discovery of many unusual and showy specimens of secondary phosphates found within fractures of beryl and feldspar. Vern Stratton, who was performing the mining operations at the time, had developed an eye for unusual mineral occurrences in Black Hills pegmatites from his mining experience over the years; an awareness that he developed through his father, Louis Stratton. Vern had brought in several very showy specimens to the museum to show Bill Roberts, keenly knowing how Bill would react because of Verne's previous experiences with Bill concerning unusual mineral finds in Black Hills pegmatites. Bill was usually very good about concealing his excitement over new mineral finds that were brought to his attention, just in case he might want to acquire a piece or two for the museum and himself. Upon Vern displaying the selection of varicolored Tip Top specimens on the beryl and feldspar matrices, Bill's usual "poker face" was replaced by eyes growing to the size of silver dollars and tipping his glasses to the front of his nose and immediately began peering over the top of them in his usual manner. He immediately blurted out "Where did you get these?" in a very deep and serious tone, and Vern proceeded to tell Bill about the circumstances resulting in the new find at the Tip Top. After our initial perusal of some of the specimens and upon a more thorough examination of them after Vern had left, we came to the rapid conclusion that some of the minerals found on these specimens were very good candidates for new species. Bill's excitement and enthusiasm levels were raised to levels that far surpassed his usual high levels. We (Campbell and Roberts) began immediate qualitative work on many of the species and initiated cooperative work with Dr. Pete Dunn of the Smithsonian Institution.  

As the next couple of weeks advanced and as our research was progressing, it came to Bill's attention that someone had acquired an assortment of specimens from this new find from Vern. Bill had attempted negotiations with Vern for as much of the material as could obtain, anticipating that much of it possessed a relative abundance of these unusual and potentially new minerals, but with only very limited success. Bill became very concerned and fixated about the material being distributed since he did not want us to be "scooped" on the research and because it was the most significant mineral find Bill had been associated with and it was the basis for my (Campbell's) master's thesis. This was a founded concern since we had learned that another individual, who was supposedly working cooperatively with us had begun his own analyses and had sent some of the material off to others for analytical work. One day at the height of Bill's emotional level of the events that were transpiring, Bill awoke in the morning from a night of little sleep and was preoccupied with thought of our research, trying to negotiate with Vern over specimen acquisition, and concerned over underhanded research efforts. Bill's concern and anxiety rose to the point that as he proceeded to prepare himself for the morning and leave for work at the museum as usual, he went down to the garage, started his "monkey-puke yellow" Chevy station wagon, put it in reverse, gave it the gas and proceeded to plow through the unopened garage door behind him. By the time Bill reached the museum and I came to initiate another morning of work, Bill was at his desk with his eyes red and crossed and wearing a look on his face, never before seen by me, of deep consternation, and not to mention a bad hair day. With much apprehension because of the look I was witnessing, I muttered a weak, "Are you OK?”, a stupid question that had already been obviously answered by his look and appearance. He immediately responded that he was in a "fit of peak" and proceeded to relay what transpired that morning.   

Mineralogy 

Mineralogical work on the Tip Top mine largely began with Moore (1974). Subsequent to this initial work, which described three new species, Campbell’s master’s thesis of 1984 became the most definitive work-up to date on the Tip Top. This work should be used in conjunction with the 1986 Mineralogical Record article, along with papers that described the many new species discovered; these are listed with the references. As a result of the combined research efforts of Roberts and Campbell, five new species were discovered including ehrleite, fransoletite, tinsleyite, tiptopite and pahasapaite. It should also be noted that it is the micro analytical expertise of mineralogists such as Pete Dunn, Joel Grice, Tony Kampf, Dale Newbury, Don Peacor, Roland Rouse, George Robinson, Peter Leavens, and many others, that enabled the characterization of many of the recent new species from this locality.  

The Tip Top mine can claim at least 85 mineral species with 64 of these being phosphates and eleven of these are type locality.  Only Hagendorf – Sud in Bavaria and possibly Palermo #1 quarry in New Hampshire can claim more phosphate species. Below is a list of confirmed phosphate species found at the Tip Top mine.  An unknown described in Campbell and Roberts (1986) as the “soon-to-be-described” phosphate was named pahasapaite. 

Ehrleite with Parascholzite micro crystals to 1.5mm, Tip Top mine.
Museum of Geology type specimen, Tom Loomis photo.

Confirmed Phosphate Species at the Tip Top Mine

Confirmed Phosphate Species at the Tip Top Mine

As noted earlier, the Mineralogical Record article by Campbell and Roberts (1986), describes the majority of the rare phosphates minerals found at the Tip Top. In that article, two major alteration assemblages are given: (1) minerals derived by hydrothermal attack of triphylite and silicate minerals including beryl and (2) minerals derived by hydrothermal attack of triphylite. The reader is referred to the above reference for further details. Minor additions and comments are provided here.  

The alteration of beryllium silicates are generally thought to have formed or have associated with tiptopite, pahasapaite, whiteite, englishite, white to yellow montgomeryite, roscherite, fairfieldite, fransoletite, parafransoletite and hurlbutite. In fact, to the best of the authors’ knowledge, pahasapaite, fransoletite, parafransoletite and ehrleite have thus far been located exclusively on beryl matrix. Beryl occurs throughout the intermediate zones of the pegmatite and in fracture filling units that transect these zones. 

Tiptopite radial, acicular spray to about 0.75mm, Tip Top mine.
Tom Loomis specimen and photo

Tiptopite, acicular white sprays to about 1mm on red Roscherite
with Englishite white spheroids to about 0.2mm, Tip Top mine.
Gary Grenier photo

Tiptopite, acicular white sprays to about 1mm on red Roscherite
with Englishite white spheroids to about 0.2mm, Tip Top mine.
Gary Grenier photo

The authors thought it would benefit the readers to pull together several other mineralogical findings during the past 20 years. Since the Mineralogical Record in 1986 several new species to the Tip Top mine and/or to the mineral world have been identified including, but not limited to: cyrilovite, hopeite, kingsmountite, pahasapaite, pararobertsite, and wardite. Furthermore, the whiteite group has been re-described as well as jahnsite, which is included within the whiteite group. Wilson (1987) included a note from Sid Williams in the Mineralogical Record stating that cyrilovite was confirmed and occurred as “an unusual red brown cluster of equant to elongated crystals” at the Tip Top. In the same note it is stated that kingsmountite was also confirmed. Martin Jensen confirmed hopeite (Wilson, 1987) as white, orthorhombic, lath-like crystals to 2mm. Jensen also confirmed the occurrence of wardite as psuedo-octahedral crystals to 4mm associated with ferrisicklerite, mitridatite, pink whitlockite and red montgomeryite. Wardite occurs as splendid, yellowish, dipyramidal (psuedo-octahedral) crystals to 2mm at the Tip Top. A few comments and descriptions are provided below for the whiteite group of minerals, pahasapaite, parafransoletite and pararobertsite. 

Whiteite & Jahnsite group 

Moore (1978) was the first to describe whiteite, the Al³⁺ analogue of jahnsite, as occurring at Ilha de Taquaral, Minas Gerais, Brazil. Moore states, “owing to variable oxidation states and gross similarities in physical properties, the basic aluminum and ferric phosphates (i. e. jahnsite and whiteite, as discussed in his study) are among the most perplexing in descriptive mineralogy….”. Moore further proposed that for the general formula XM(1)M(2)₂M(3)₂(OH)₂(H₂O)₈[PO₄]₄ jahnsite-whiteite series, M(3) distinguishes jahnsites from whiteites, where Fe³⁺ > Al³⁺ for jahnsites and Al³⁺ > Fe³⁺ for whiteites. Also, unlike whiteite, jahnsite crystals are nearly always prismatic and striated parallel to [010]. Although Moore (1978) concludes: “…there is no evidence as yet that solid solution between the two is extensive – no such compositions have been found – but there is no structural reason to suspect why such solution could not exist”.   Moore’s proposal has withstood the test of time has generally been accepted.  Mandarino (1999) provides the same nomenclature and also groups three different jahnsites with three different whiteites.

Whiteite (CaMnMg), yellow equant crystals to 0.75mm on red Roscherite
Tip Top mine.
Tom Loomis specimen and photo.

Whiteite (CaMnMg), yellow equant crystals to 1mm on red Roscherite
Tip Top mine.
Chris Korpi specimen, Gary Grenier photo

Whiteite is not common at the Tip Top mine. As of yet, whiteite at the Tip Top occurs only in roscherite-bearing assemblages on beryl matrix and rarely on perthite (Campbell, 1984). Campbell (1984) describes whiteite from the Tip Top as yellowish, vitreous to resinous prismatic to sub-parallel crystals to 4mm, sometimes etched and displaying a pink core and also states that whiteite has morphology essentially identical to that of jahnsite and that other forms of whiteite exist at the Tip Top. Since Campbell’s thesis in 1984, whiteite from the Tip Top was reanalyzed (Grice, 1989). Grice states that the X-ray powder diffraction pattern of whiteite from the Tip Top closely resembled that whiteite from the type locality of Lavra da Ilha pegmatite in Brazil. However, since many phosphate minerals from the Tip Top pegmatite were deficient in iron, a detailed study was initiated. Electron-microprobe analysis subsequently verified a new species, whiteite – (CaMnMg). Whiteite occurs as individual, dull bipyramidal crystals or anhedral, etched blebs (Grice, 1989).  

Moore (1974) originally described jahnsite as a new mineral species occurring at the Tip Top mine. Mrose (1955) described a “golden rockbridgeite” from the Fletcher and Palermo mines in New Hampshire. Moore (1978) using the proposed nomenclature described above renamed the type jahnsite from the Tip Top as jahnsite – (CaMnMg). Moore also interpreted Mrose’s material as variant of jahnsite and subsequently proposed the mineral jahnsite – (CaMnFe). Campbell (1984) described jahnsite from the Tip Top as highly variable and states “jahnsite and the jahnsite-like varieties vary widely in morphology and color”.  Since then, two other jahnsite species have been approved at other localities; these are jahnsite – (CaMnMn) and jahnsite – (MnMnMn). Jahnsites can only be distinguished with certainty by analytical methods. Below are general descriptive guidelines, which may be used.

Jahnsite - (CaMnMg)
Type Locality - Tip Top mine, South Dakota
Reference – Moore (1974) with update in Moore (1978)
Jahnsite is monoclinic and occurs as tabular to long prismatic crystals to 7mm with vitreous to subadamantine luster. Color varies from nut-brown, purplish-brown, yellow, yellow-orange to greenish-yellow. Crystals are commonly twinned, striated parallel to the prism [010], which distinguish it from hureaulite and leucophosphite. Jahnsite is easily confused with laueite, psuedolaueite, stewartite, and childrenite. (Twinning results in an orthorhombic appearance, easily confused for segelerite.) Campbell (1984) further describes jahnsite as single crystals, clusters and sub parallel groups. Jahnsite occurs in altered triphylite and associated with rockbridgeite, hureaulite, leucophosphite and sometimes tavorite. 

Jahnsite - (CaMnMg) to 1mm, Tip Top mine.
Tom Loomis specimen and photo

 Jahnsite - (CaMnFe)
Type locality – Fetcher mine, New Hampshire
Reference –Moore (1978) with reference in Moore(1974)
Based upon Mrose (1955), jahnsite occurs at the Fletcher pegmatite as yellow brown crystals and with sheaflike aggregates. Jahnsite from the Fletcher pegmatite is also described as orange “splinters” intergrown with coarse fibrous black rockbridgeite. Anthony (2000) describes jahnsite – (CaMnFe)  “as bladed crystals and warty crystal aggregates, to 3mm”.  Jahnsite - (CaMnFe) has not been confirmed at the Tip Top although the possibilities are good that it does exist.

 Jahnsite – (CaMnMn)
Type locality – Mangualde pegmatite, Beira, Portugal
Reference –Grice (1990)
Occurs at the Mangualde pegmatite as brownish to brownish yellow, equant, and subhedral to euhedral crystals up to 0.5mm.  Crystals are transparent with a vitreous luster and occur with phosphosiderite, zodacite, varulite, and microcline.  

Jahnsite – (MnMnMn)
Type locality – Stewart mine, Pala, California
Reference – Moore (1978)
Found within a mixture of hureaulite and jahnsite in the so-called “salmonsite” at the Stewart mine. A clear description was not found. 

Pahasapaite

Reference – Rouse et al (1987)
Occurs as euhedral and malformed, transparent, colorless to light pink, and vitreous crystals to about 1.0 mm. Pahasapaite is unusual in that it is an isometric phosphate, with a zeolite like structure. Pahasapaite occurs with other beryllophosphates in seams of fractured beryl crystals and are associated with montgomeryite, tiptopite, eosphorite-childrenite, and dark olive-green roscherite. Thus far, pahasapaite has been known to occur exclusively on beryl matrix specimens. The “undescribed phosphate” in figure 31 of Campbell and Roberts (1986) is pahasapaite, which was discovered by Tom Campbell. Pahasapaite is extremely rare. 

Pahasapaite crystal to 1mm, Tip Top mine
Chris Korpi specimen, Gary Grenier photo

Parafransoletite

Reference – Kampf et al  (1992)
Parafransoletite occurs as colorless to white spear-shaped blades, most typically as sheaf- and bow tie –like aggregates and clusters of radial sprays to 2mm. Individual crystals are usually no more than 0.4 mm.  Like pahasapaite, parafransoletite has thus far been found exclusively on fracture seams of beryl. Parafransoletite is the triclinic dimorph of fransoletite and is extremely rare. Parafransoletite was found on material collected in 1983 by Martin Jensen and Vern Stratton and was associated with roscherite, montgomeryite, mitridatite, whitlockite and englishite.

Parafransoletite, Tip Top mine. Micro crystals to about 0.5mm, Tip Top mine.
Chris Korpi specimen, Tom Loomis photos.

Pararobertsite

Reference – Roberts et al (1989)
Pararobertsite occurs as thin, dark red transparent single plates to 0.2 mm on whitlockite and associated with carbonate-apatite and smoky quartz. Scanning electron photomicrograph shows crystals as thin, parallel, somewhat divergent, spear-shaped plates 0.02 mm thick. Pararobertsite is very rare. Like robertsite, the late Bill Roberts discovered pararobertsite. 

Tinsleyite

Several of the phosphate species at the Tip Top mine are microscopic in size and many cannot be easily identified just by sight.  A good example is the mineral tinsleyite, which occurs as magenta-red, thin layers on leucophosphite.  The mineral is the aluminum analog of leucophosphite and color is not necessarily a key diagnostic as not all magenta colored crystals are tinsleyite.  X-ray diffraction analysis of suspected tinsleyite will not provide conclusively that the mineral is in fact tinsleyite.  Optical and/or microprobe analysis is required for definitive identification.  There are in fact very few specimens that have been positively identified as being tinsleyite. It is entirely possible that this species is more prevalent than originally thought and careful optical analysis of magenta-red leucophosphite specimens may yield additional specimens.

Postscript 

A small housing tract has been developed at the edge of the old Tip Top mine dumps.  As a result of these home sites the Forest Service has placed a chain link fence around the pit. The pit has been flooded and is extremely dangerous. Since private property basically surrounds the mine access is all but forbidden. The old dumps are highly “picked over” and collectors in search of phosphate minerals have ruthlessly hammered most triphylite nodules to walnut size pieces. Beryl specimens are essentially extremely hard to find at the Tip Top. The dumps are also heavily overgrown. 

Through the years many fine collections of Tip Top specimens have been assembled. Probably the two most important collections are those of the Museum of Geology at South Dakota School of Mines in Rapid City and that of the Black Hills Institute of Geological Research in Hill City. A significant collection can also be found at the Smithsonian in Washington, D. C., which was the depository for specimens collected during important studies of the 1940’s through 1960’s. Other fine collections reside in several private collections around the world.

The Tip Top mine, flooded. Photo taken in 2001 by Tom Loomis

Acknowledgements

The authors would like to extend their thanks and appreciations to Bob Farrar of the Black Hills Institute of Geological Research for helpful advice and review of this article. Special thanks go to Chris Korpi, who has provided dozens of specimens for photography and helpful research. Chris has been instrumental in reassembling many important specimens from the late Bill Roberts collection. Chris also provided much needed background of historical events for this article. 

Special Notice

Please note: Access to most of the mines in the Black Hills are restricted if not all together forbidden. Most of the mines mentioned in this article are within private property and permission must be given by the landowner for entry. In many cases the entry will be denied. As with all mines, dangerous conditions exist. Holes, rock walls, shafts, water hazards, equipment, blasting material, large boulders, dangerous rock slopes and many other hazards endanger your safety. The author and any aforementioned groups and /or organizations including MATRIX magazine will not give permission to enter any mine property and thus will not assume any liability whatsoever. 

References

 Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (2000) Handbook of Mineralogy Volume IV. Mineral Data Publishing, Tucson, Arizona. 

Campbell, T. J (1984) Phosphate Mineralogy of the Tip Top pegmatite. Unpublished M.S. thesis, South Dakota School of Mines and Technology. 172 p. 

Campbell, T. J., and W. L. Roberts (1986) Phosphate minerals from the Tip Top pegmatite mine, Black Hills, South Dakota.  Mineralogical Record 17, 237-54 

Dunn, P. J., W. L. Roberts, T. J. Campbell, and P. B. Leavens  (1983) Red montgomeryite and associated minerals from the Tip Top pegmatite with notes on kingsmountite and calcioferrite.  Mineralogical Record 14: 195-97 

Dunn, P. J., R. C. Rouse, T. J. Campbell, and W. L. Roberts (1984) Tinsleyite, the aluminum analogue of leucophosphite from the Tip Top pegmatite in South Dakota.  American Mineralogist 69:374-76. 

Farrar, B. - Black Hills Institute of Geological Research (2002) pers. comm. 

Fisher, D. J. (1942) Preliminary report on some pegmatites of the Custer district. South Dakota Geol. Survey Report of Investigations, No. 44. 

Grice, J. D., Dunn, P. J., Ramik, A. (1990) Jahnsite – (CaMnMn), a new member of the whiteite group from Mangualde, Beira, Portugal. American Mineralogist 75:401-404 

Grice, J. L., Peacor, D. R., Robinson, G. W., Van Velthuizen, J., Roberts, W. L., Campbell, T. J., Dunn, P. J. (1985) Tiptopite, A new mineral species from the Black Hills, South Dakota

Grice, J. D., Dunn, P. J., and Ramik, R. A., (1989): Whiteite- (CaMnMg), a new mineral species from the Tip Top pegmatite, Custer, South Dakota. Canadian Mineralogist 27, 699-702.

Kampf, A. R., P. J. Dunn, and E. E. Foord (1992) Parafransoletite, a new dimorph of fransoletite from the Tip Top pegmatite, Custer, South Dakota.  American Mineralogist 77:843-47.  

Mandarino, J. A. (1999) Fleischer’s Glossary of Mineral Species 1999.  The Mineralogical Record, Tucson, Arizona. 

Moore, P. B. (1973) Pegmatite phosphates: Descriptive mineralogy and crystal chemistry.  Mineralogical Record 4: 103-30. 

Moore, P. B. (1974) Jahnsite, segelerite and robertsite: Three new transition metal phosphates species.  American Mineralogist 59:48-55. 

Moore, P. B. and Ito, J. (1978) Whiteite, a new species, and a proposed nomenclature for the jahnsite-whiteite complex series. Mineralogical Magazine v. 42, n. 323. 

Mrose, M. E. (1955) Problems of the iron-manganese phosphates. Geol. Soc. Am. 1955 Program Abstr. 76A. 

Page, L. R. and others (1953) Pegmatite Investigations 1942-1945, Black Hills, South Dakota, Geological Survey Prof. Paper 247. 

Peacor, D. R., Dunn, R. J., Roberts, W. L., Campbell, T. J., and Newbury, D., (1983) Fransoletite, a new calcium beryllium phosphate from the Tip Top pegmatite, Custer, South Dakota.  Bulletin de Mineralogie 106: 449-503. 

Roberts, W. L., and G. Rapp Jr. (1965) Mineralogy of the Black Hills. South Dakota School of Mines bulletin 18. 

Roberts, W. L., Rapp, G., and Weber, J. (1974) Encyclopedia of Minerals.  Van Nostrand Reinhold Co., New York, U.S.A. 

Rouse, R. C., Peacor, Dunn, P. J., Campbell, T. J., Roberts, W. L., Wicks, F, J., Newbury, D. (1987) Pahasapaite, a beryllophosphate zeolite related to synthetic rho, from the Tip Top pegmatite of South Dakota. Neues Jahrd. Mineral. Mon., 433-440. 

Triscori, K. L., and T. J. Campbell, (1986) Type locality minerals of the Black Hills, South Dakota. Mineralogical Record 17: 297-302. 

Wilson, W. E. (1987) Letter from Martin Jensen on Tip Top mine minerals.  Mineralogical Record 18: 167-72. 

Wilson, W. E. (1987) Letter from Sid Williams on Tip Top mine minerals. Mineralogical Record 18: 359-368.