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Tsumeb Rare Mineral Specimens III

Friday, 27 November 2015 08:00 AM

A fresh load of rarities from Tsumeb!

Chalcocite

with Siderite - #42753
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
Cu2
Availability
Sold
Size
5.5 x 2 x 3 cm - Sm Cabinet 
Tagged
sulfide , copper  

Elongated needle Chalcocite crystals to 8mm, some look to be spinel twins with discoidal Siderite.


Chalcocite

Formula
Cu2
Crystal System
Monoclinic 
Crystal Habit
Massive, Granular, Euhedral Crystals 
Cleavage
Indistinct, None, None 
Luster
Metallic 
Color
blue black, gray, black, black gray, steel gray 
Streak
grayish black 
Class
Monoclinic - Prismatic 
Fracture
Conchoidal 
Hardness
2.5-3 

Dioptase

on Calcite - #42751
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
CuSiO3·H2
Availability
Sold
Size
6 x 5 x 3 cm - Sm Cabinet 
Tagged
copper  

Preferentially crystallized Dioptase micro crystals on Cacite rhombs. This is really a beautiful specimen.


Dioptase

Formula
CuSiO3·H2
Crystal System
Trigonal 
Crystal Habit
Massive, Cryptocrystalline, Crystalline - Coarse 
Cleavage
Good, None, None 
Luster
Vitreous (Glassy) 
Color
dark blue green, emerald green, turquoise 
Streak
green 
Class
Trigonal - Rhombohedral 
Fracture
Conchoidal 
Hardness
Mineralpedia
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Dioptase

with Duftite - #PD43269
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
CuSiO3·H2
Availability
Sold
Size
4.5 x 3 x 3 cm - Miniature 
Tagged
copper  

Glassy emerald green (not blue) Dioptase crytsals to 6mm with green Duftite.


Dioptase

Formula
CuSiO3·H2
Crystal System
Trigonal 
Crystal Habit
Massive, Cryptocrystalline, Crystalline - Coarse 
Cleavage
Good, None, None 
Luster
Vitreous (Glassy) 
Color
dark blue green, emerald green, turquoise 
Streak
green 
Class
Trigonal - Rhombohedral 
Fracture
Conchoidal 
Hardness
Collection
Phillips Collection
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Djurleite

with Chalcocite - #38373
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
Cu31S16 
Availability
Sold
Size
3 x 2 x 1.5 cm - Thumbnail 
Tagged
sulfide , copper  

An good specimen loaded with 2-5mm striated crystals of Djurleite and Chalcocite. Ex. Gebhard. 3rd Oxidation zone.


Djurleite

Formula
Cu31S16 
Crystal System
Monoclinic 
Crystal Habit
Prismatic, Tabular, Massive - Granular 
Cleavage
None, None, None 
Luster
Metallic 
Color
lead gray, blue black, black, black gray 
Streak
metallic 
Class
Monoclinic - Prismatic 
Fracture
Brittle - Conchoidal 
Hardness
2.5-3 

Dolomite

#DS43252
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
CaMg(CO3)2 
Availability
Sold
Size
5 x 4 x 2.5 cm - Miniature 
Tagged
carbonate  

Pink rhombic crystals mostly to 3mm but also having larger 7mm crystals perched at the top.


Dolomite

Formula
CaMg(CO3)2 
Crystal System
Trigonal 
Crystal Habit
Crystalline - Coarse, Massive, Blocky - Rhombohedral 
Cleavage
Perfect, Perfect, Perfect 
Luster
Vitreous (Glassy) 
Color
white, gray, reddish white, brownish white, gray 
Streak
white 
Class
Trigonal - Rhombohedral 
Fracture
Brittle - Conchoidal 
Hardness
3.5-4 
Collection
Phillips Collection
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Galena

with Cerussite - #PD42010
Locality
Tsumeb mine, Tsumeb, Namibia 
Formula
PbS 
Availability
Sold
Size
8.5 x 4.5 x 3 cm - Sm Cabinet 
Tagged
sulfide  

Dull grey Galena crystals, seemingly etched or partially corroded each with at least one fine Cerussite crystal beside it. The Cerussite crystals reach 9mm and are typically twinned and exhibiting the usual adamantine luster. Galena was the main ore of lead at Tsumeb, but surprisingly you just don't see it often on the market.


Galena

Formula
PbS 
Crystal System
Isometric 
Crystal Habit
Euhedral Crystals, Massive - Granular, Massive 
Cleavage
Perfect, Perfect, Perfect 
Luster
Metallic 
Color
light lead gray, dark lead gray 
Streak
grayish black 
Class
Isometric - Hexoctahedral 
Fracture
Brittle 
Hardness
2.5 
Collection
Phillips Collection
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