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Southeast US Phosphates

Thursday, 23 April 2020 08:00 PM

Introducing the "Southeast US Phosphates" gallery which is part of our Special Edition galleries. This gallery contains mineral specimens for sale including straczekite, strengite and more from places like Union Carbide mine, Wilson Springs, Garland Co., Arkansas, United States, Three Oaks Gap, Polk Co., Arkansas, United States, Indian Mountain, Cherokee Co., Alabama, United States, and Jacksonville Road Cut, near Jacksonville, Calhoun Co., Alabama, United States.

Straczekite

#DO53041
Locality
Union Carbide mine, Wilson Springs, Garland Co., Arkansas, United States 
Formula
(Ca,K,Ba)V8O20·3H2
Availability
Sold
Size
4 x 3.5 x 2 cm - Miniature 
Tagged
vanadium  

Not a phosphate, but for sake of semi-completeness, it is here on this update because it is a good, rare mineral. Straczekite is tar black and crystallizes in plates grouped in curled-up balls. They are quite weird looking actually. You can't find them anywhere else. It's a four-locality mineral.


Straczekite

Formula
(Ca,K,Ba)V8O20·3H2
Crystal System
Monoclinic 
Crystal Habit
Microscopic Crystals, Fibrous 
Cleavage
Perfect, None, None 
Luster
Greasy (Oily) 
Color
greenish black 
Streak
greenish black 
Class
Monoclinic - Prismatic 
Hardness
1-2 
Collection
Don Owens Collection

Straczekite

#DO53042
Locality
Union Carbide mine, Wilson Springs, Garland Co., Arkansas, United States 
Formula
(Ca,K,Ba)V8O20·3H2
Availability
Sold
Size
5 x 4 x 3 cm - Miniature 
Tagged
vanadium  

No, this is not a phosphate! Sorry. Straczekite is a rare black mineral with vanadium and these are exceptional crystals. They are platy and occur in curled-up groups to around 1mm.


Straczekite

Formula
(Ca,K,Ba)V8O20·3H2
Crystal System
Monoclinic 
Crystal Habit
Microscopic Crystals, Fibrous 
Cleavage
Perfect, None, None 
Luster
Greasy (Oily) 
Color
greenish black 
Streak
greenish black 
Class
Monoclinic - Prismatic 
Hardness
1-2 
Collection
Don Owens Collection

Strengite

with Kidwellite - #BN53052
Locality
Three Oaks Gap, Polk Co., Arkansas, United States 
Formula
Fe3+PO4·2H2
Availability
Sold
Size
6 x 4.5 x 3.5 cm - Sm Cabinet 
Tagged
phosphate  

The Kidwellite from Three Oaks is perhaps the best around. The digital camera unfortunately washes out the green. The first photo (and this goes with the rest of the specimens in this website update) shows the true color best. It is a lime green of sorts and is a microcrystalline crusts which covers a layer of deep red Beraunite, which is shown in the last two photos. Upon the Kidwellite are at least a dozen Strengite spheres. These are a nice sparkly purple and measure up to about 1.5mm.

These are no longer available. They came from the Dr. Buford Nichols collection who collected them along with Dr. Albert Kidwell himself. According to the late, great Art Smith in his book "Collecting Arkansas Minerals" the locality is collected out and obliterated. It requires a four-wheel drive to get there. 


Strengite

Formula
Fe3+PO4·2H2
Crystal System
Orthorhombic 
Crystal Habit
Spherical, Radial, Botryoidal 
Cleavage
Good, Poor, None 
Luster
Vitreous (Glassy) 
Color
colorless, pale violet, deep violet, red, carmine red 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Conchoidal 
Hardness
3.5 
Collection
Dr. Buford Nichols Collection
Mineralpedia
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On Dakota Matrix
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Strengite

with Cacoxenite on Beraunite - #BN53054
Locality
Three Oaks Gap, Polk Co., Arkansas, United States 
Formula
Fe3+PO4·2H2
Availability
Sold
Size
3.5 x 2 x 1.5 cm - Miniature 
Tagged
phosphate  

A thumbnail size specimen of stunning perfection and beauty. The purple is naturally the Strengite crystals which have coalesced into spherical groups to 1.5mm. They are golden fibrous Cacoxenite which in turn are on red Beraunite. 

Keep in mind that these specimens are a thing of the past and are no longer collected or mined. The locality has been obliterated.


Strengite

Formula
Fe3+PO4·2H2
Crystal System
Orthorhombic 
Crystal Habit
Spherical, Radial, Botryoidal 
Cleavage
Good, Poor, None 
Luster
Vitreous (Glassy) 
Color
colorless, pale violet, deep violet, red, carmine red 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Conchoidal 
Hardness
3.5 
Collection
Dr. Buford Nichols Collection
Mineralpedia
View Strengite
On Dakota Matrix
Previously Sold Strengite
On Dakota Matrix
Other Available Strengite
WebMineral
View Strengite
Mindat
View Strengite

Strengite

with Kidwellite - #BN53064
Locality
Indian Mountain, Cherokee Co., Alabama, United States 
Formula
Fe3+PO4·2H2
Availability
Sold
Size
4 x 3.5 x 3 cm - Miniature 

A cavity lined with light purple, free-standing bladed groups of Strenite to about 1mm. Bladed Strengite the rare crystal form of Strengite. The other Strengite entries in these pages are spheroidal groups. Lining the edges of the vug is green Kidwellite. 


Strengite

Formula
Fe3+PO4·2H2
Crystal System
Orthorhombic 
Crystal Habit
Spherical, Radial, Botryoidal 
Cleavage
Good, Poor, None 
Luster
Vitreous (Glassy) 
Color
colorless, pale violet, deep violet, red, carmine red 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Conchoidal 
Hardness
3.5 
Collection
Dr. Buford Nichols Collection
Mineralpedia
View Strengite
On Dakota Matrix
Previously Sold Strengite
On Dakota Matrix
Other Available Strengite
WebMineral
View Strengite
Mindat
View Strengite

Strengite

with Cacoxenite & Beraunite - #BN53065
Locality
Jacksonville Road Cut, near Jacksonville, Calhoun Co., Alabama, United States 
Formula
Fe3+PO4·2H2
Availability
Sold
Size
8 x 5 x 4 cm - Sm Cabinet 
Tagged
phosphate  

As you can see by the number of photos, I was really impressed by this specimen. Not only are there fine, bladed Strengite to 1mm, but there are free-standing deep red Beraunite crystals. In fact, it is the only specimen in this gallery with free-standing Beraunite crystals. Again, these could be Eleonorite. But that is splitting hairs. They are both hydrated iron phosphates. Eleonorite does not have ferrous iron in it's structure and so has one less hydroxyl radical. But I must admit, I have never seen red Beraunite like this from a pegmatite. In pegmatites the Beraunite is typically green to rusty red acicular sprays. Albeit two totally different geological environments.

Elsewhre on this specimen are Cacoxenite "beads". They seem to have been attracted to the Beraunite as seen in the photos with free-standing Beraunite. 

The specimen is a mind blower under the scope.


Strengite

Formula
Fe3+PO4·2H2
Crystal System
Orthorhombic 
Crystal Habit
Spherical, Radial, Botryoidal 
Cleavage
Good, Poor, None 
Luster
Vitreous (Glassy) 
Color
colorless, pale violet, deep violet, red, carmine red 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Conchoidal 
Hardness
3.5 
Collection
Dr. Buford Nichols Collection
Mineralpedia
View Strengite
On Dakota Matrix
Previously Sold Strengite
On Dakota Matrix
Other Available Strengite
WebMineral
View Strengite
Mindat
View Strengite

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