mineral specimens
rare minerals
mineral dealer
systematic minerals
Black Hills minerals
fine minerals
mineral dealer
Dana minerals
IMA minerals
mineral collections
rock and minerals
gem crystal
0 item @ $0.00  

Black Hills Minerals

Thursday, 22 November 2012 09:00 AM

The Black Hills, area of 80 x 240km, is home to over 300 mineral species. Species are found in a variety of geological environments including metallic vein deposits, large scale hydrothermally altered deposits, subterranean alpine, passive sedimentary, metamorphic, and of course pegmatite deposits. By and large most of the minerals are silicates and secondary phosphates. We love the Black Hills for this diversity. Don't miss this one, you'll be surprised at what we pull out.

Baryte

#PD34516
Locality
Elk Creek, Meade Co., South Dakota, United States 
Formula
BaSO4 
Availability
Sold
Size
6.5 x 6 x 4 cm - Sm Cabinet 

Typically you see these huge beautiful crystals of Baryte from Elk Creek. They are world renowned. But here is an affordable, but nice, golden Baryte from Elk Creek with dozens of crystals to over 1cm all nicely terminated with just a few broken. I didn't take a photo of it, but the side shows part of the ammonite in which the Baryte crystals formed.


Baryte

Formula
BaSO4 
Crystal System
Orthorhombic 
Crystal Habit
Tabular, Prismatic, Massive - Fibrous 
Cleavage
Perfect, Perfect, Imperfect 
Luster
Vitreous (Glassy) 
Color
white, yellowish white, grayish white, brownish white, dark brown 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Uneven 
Hardness
3-3.5 
Collection
Phillips Collection
Mineralpedia
View Baryte
On Dakota Matrix
Previously Sold Baryte
On Dakota Matrix
Other Available Baryte
WebMineral
View Baryte
Mindat
View Baryte
SOLD
Baryte - PD34518
Baryte - PD34518

Baryte

#PD34518
Locality
Pierre Fm, Meade Co., South Dakota, United States 
Formula
BaSO4 
Availability
Sold
Size
8.5 x 5.5 x 5 cm - Sm Cabinet 

Ammonite with clear crystals of Baryte to 1cm.


Baryte

Formula
BaSO4 
Crystal System
Orthorhombic 
Crystal Habit
Tabular, Prismatic, Massive - Fibrous 
Cleavage
Perfect, Perfect, Imperfect 
Luster
Vitreous (Glassy) 
Color
white, yellowish white, grayish white, brownish white, dark brown 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Uneven 
Hardness
3-3.5 
Collection
Phillips Collection
Mineralpedia
View Baryte
On Dakota Matrix
Previously Sold Baryte
On Dakota Matrix
Other Available Baryte
WebMineral
View Baryte
Mindat
View Baryte
SOLD
Bobdownsite-Whitlockite - 34508
Bobdownsite-Whitlockite - 34508

Bobdownsite-Whitlockite

#34508
Locality
Tip Top mine, Custer Co., South Dakota, United States 
Formula
Ca9Mg(PO4)6(PO3F) 
Availability
Sold
Size
7 x 4 x 2.5 cm - Sm Cabinet 
Tagged
phosphate  

An excellent specimen of rich clear rhombs of Bobdownsite on pink orthoclase matrix. We have hyphenated it with Whitlockite as the jury is still out on this identification. It may be both. Raman analyses at the RRUFF project has thus shown all Whitlockites from the Tip Top mine to be Bobdownsite. But there is a chance that fluorine maybe detected by inclusions of fluorapatite in the crystals. It is very difficult to distiguish F from OH with EDS without doing a polished section. Whatever the case, it is academic and not really important in the overall scheme and parageesis of pegmatitic mineralogy (or is it?). We look forward to your comments. You will find a good thread on Mindat.

A case in point: Look close at these photos. There are sprays of white apatite scattered about the surfaces of the Bob-Whit xls. These may be carbonate apatite but may contain Fluorine to some degree.


SOLD
Carbonate Apatite - 34509
Carbonate Apatite - 34509

Carbonate Apatite

#34509
Locality
Tip Top mine, Custer Co., South Dakota, United States 
Availability
Sold
Size
6 x 4.5 x 4.5 cm - Sm Cabinet 
Tagged
phosphate  

A nice botryoidal thick coat of "carbonate apatite" on Feldspar. Nice!


Columbite-(Fe)

with Montebrasite - #PD34521
Locality
Custer dist., Custer Co., South Dakota, United States 
Formula
Fe2+Nb2O6 
Availability
Sold
Size
7 x 6 x 3.5 cm - Sm Cabinet 

We do not have a specific locality for this specimen, however if I had to choose it would be Tin Mountain, which is rich in Montebrasite. the large, dull black Ferrocolumbite crystal attached to the Montebrasite shows a few good faces and is 4 x 4.5cm and is 1.3cm wide. The Black Hills are known for their zoned pegmatites and the "Columbite-Tantalite" series is found in most of them. Some of the more well-known mines include the Tin Mountain as well as the Etta, Nickel Plate, Ingersoll and Dan Patch. Historically, these have been lumped into the series 'Columbite-Tantalite' or "Col-Tan" and more properly called the Columbite-(Fe)-Tantalite-(Fe) series, which covers the range of compositions rich in Niobium(Nb) to Tantalum(Ta). It is impractical to test the composition of all of them, although I believe most are high in iron.


Columbite-(Fe)

Formula
Fe2+Nb2O6 
Crystal System
Orthorhombic 
Crystal Habit
Massive - Granular, Striated 
Cleavage
Distinct, None, None 
Luster
Sub Metallic 
Color
black, brownish black 
Streak
blackish brown 
Class
Orthorhombic - Dipyramidal 
Fracture
Sub Conchoidal 
Hardness
Collection
Phillips Collection

Englishite

with Roscherite group - #34507
Locality
Tip Top mine, Custer Co., South Dakota, United States 
Formula
K3Na2Ca10Al15(OH)7(PO4)21·26H2
Availability
Sold
Size
6.5 x 3 x 3 cm - Sm Cabinet 
Tagged
phosphate , beryllium  

Interesting assemblage of phosphates with a lot of cotton-like balls of Englishite to maybe 0.3mm associated with a dark green Roscherite group member, which may indeed be Greifensteinite, the Fe member of the Roscherite group, as tested by Igor Pekov. There are several colors of Roscherites at the Tip Top and we suspect that these will eventually be sorted out to more closely match up with the growing list of Roscherites from a variety of pegmatites including Tip Top as well as Foote mine and several Brazilian localites (Sapacaia, Serra Branca etc).

Also on this specimn are groups of divergent light yellowish white Montgomeryite to 2mm.


Englishite

Formula
K3Na2Ca10Al15(OH)7(PO4)21·26H2
Crystal System
Monoclinic 
Crystal Habit
Micaceous, Aggregates, Friable 
Cleavage
Perfect, None, None 
Luster
Vitreous - Pearly 
Color
colorless, white 
Streak
white 
Class
Monoclinic - Sphenoidal 
Hardness

All photos by Dakota Matrix and are Copyrighted © and may not be used without permission. Copyright © 2014 - Dakota Matrix Minerals, Inc. Privacy | Terms & Conditions | Site Map