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Rare Minerals

Sunday, 09 January 2022 06:00 PM

Introducing the "Rare Minerals" gallery which is part of our New Additions galleries. This gallery contains mineral specimens for sale including mullite, orthopinakiolite, preiswerkite, pyrargyrite, serendibite, and silver and more from places like Loch Scridain, Isle of Mull, Argyll and Bute, Scotland, Långban, Filipstad, Värmland, Sweden, Geisspfad, Binn Valley, Wallis, Switzerland, Uchucchacua mine, Oyon prov., Lima dept., Peru, Johnsburg, Warren Co., New York, United States, and O'Brien mine, Cobalt, Ontario, Canada.

Mullite

with Corundum & Anorthite - #BW57311
Locality
Loch Scridain, Isle of Mull, Argyll and Bute, Scotland 
Formula
Al4+2xSi2-2xO10-x (x~0.4) 
Availability
Sold
Size
6 x 3.5 x 3 cm - Sm Cabinet 

Pinkish Mullite with pink corundum and light green Anorthite. Interesting locality.


Mullite

Formula
Al4+2xSi2-2xO10-x (x~0.4) 
Crystal System
Orthorhombic 
Crystal Habit
Crystalline - Fine, Prismatic 
Cleavage
Good, None, None 
Luster
Vitreous (Glassy) 
Color
colorless, violet, yellow, white, light pink 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle 
Hardness
6-7 
Collection
Bill Wilson Collection
Mineralpedia
View Mullite
On Dakota Matrix
Previously Sold Mullite
On Dakota Matrix
Other Available Mullite
WebMineral
View Mullite
Mindat
View Mullite

Orthopinakiolite

#BW57395
Locality
Långban, Filipstad, Värmland, Sweden 
Formula
Mg2Mn3+O2(BO3
Availability
Sold
Size
6.5 x 5 x 3 cm - Sm Cabinet 
Special Info
Type Locality 

Black plates of Orthopinakiolite embedded in matrix to 7mm. Rich.


Orthopinakiolite

Formula
Mg2Mn3+O2(BO3
Crystal System
Orthorhombic 
Cleavage
Good, None, None 
Luster
Metallic 
Color
black 
Streak
brown gray 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle 
Hardness
Collection
Bill Wilson Collection
Special Info
Type Locality

Preiswerkite

#BW57300
Locality
Geisspfad, Binn Valley, Wallis, Switzerland 
Formula
NaAlMg2(Si2Al2)O10(OH)2 
Availability
Sold
Size
6 x 3.5 x 3 cm - Sm Cabinet 
Special Info
Type Locality 

Preiswerkite is a rare member of the mica group, thus it forms thin plates in aggregates on serpentine(?). It is a metamorphic mineral formed in upper greenschist to lower amphibolite facies. There's not a whole lot of documentd localities, but I suspect it is looked over quite a bit given the subtle appearance. 


Preiswerkite

Formula
NaAlMg2(Si2Al2)O10(OH)2 
Crystal System
Monoclinic 
Cleavage
Perfect, None, None 
Luster
Vitreous - Pearly 
Color
greenish white, light green 
Streak
white 
Class
Monoclinic - Prismatic 
Hardness
2.5 
Collection
Bill Wilson Collection
Special Info
Type Locality

Pyrargyrite

#55553
Locality
Uchucchacua mine, Oyon prov., Lima dept., Peru 
Formula
Ag3SbS3 
Availability
Sold
Size
1.2 x 0.8 x 1.1 cm - Thumbnail 
Tagged
sulfide , silver  

A beautiful small crystal, terminated with prism faces. It is cherry red and as sweet as one too!


Pyrargyrite

Formula
Ag3SbS3 
Crystal System
Trigonal 
Crystal Habit
Massive, Crystalline - Poor, Prismatic 
Cleavage
Poor, None, None 
Luster
Sub Metallic 
Color
deep red, red gray 
Streak
cherry red 
Class
Trigonal - Ditrigonal Pyramidal 
Fracture
Brittle - Conchoidal 
Hardness
2.5 

Serendibite

with Phlogopite - #BW57303
Locality
Johnsburg, Warren Co., New York, United States 
Formula
Ca4(Mg6Al6)O4[Si6B3Al3O36
Availability
Sold
Size
5 x 5 x 2 cm - Miniature 

Bluish Serendibite with golden Phlogopite. Serendibite is found in skarn deposites and formed by boron metasomatism. 


Serendibite

Formula
Ca4(Mg6Al6)O4[Si6B3Al3O36
Crystal System
Triclinic 
Crystal Habit
Granular, Twinning Common 
Cleavage
None, None, None 
Luster
Vitreous (Glassy) 
Color
blue, blue green, gray blue, light yellow, dark blue 
Streak
white 
Class
Triclinic - Pinacoidal 
Hardness
6-7 
Collection
Bill Wilson Collection

Silver

with Safflorite - #RW57366
Locality
O'Brien mine, Cobalt, Ontario, Canada 
Formula
Ag 
Availability
Sold
Size
7.5 x 4 x 5 cm - Sm Cabinet 
Tagged
ore specimen , silver  

A crazy rich specimen of Silver occupying about 30% of the matrix with silvery, untarnished, Safflorite. The Silver is tarnished as seen in the photos. Both the Saffloite and Silver together accounts for about 70-80% of the matrix. The rest is Calcite. Excellent ore specimen.


Silver

Formula
Ag 
Crystal System
Isometric 
Crystal Habit
Arborescent, Dendritic, Massive 
Cleavage
None, None, None 
Luster
Metallic 
Color
silver white, gray white, gray 
Streak
silver white 
Class
Isometric - Hexoctahedral 
Fracture
Hackly 
Hardness
2.5-3 
Collection
Robert J. Waidler Collection
Mineralpedia
View Silver
On Dakota Matrix
Previously Sold Silver
On Dakota Matrix
Other Available Silver
WebMineral
View Silver
Mindat
View Silver

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