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0 item @ $0.00  

Metamorphic Minerals

Friday, 31 July 2015 07:30 PM

Basic minerals derived during the process of metamorphism. Nothing fancy!

Actinolite

#PD42436
Locality
Schwarzhorn, Geisspfad area, Binn Valley, Wallis, Switzerland 
Formula
Ca2(Mg,Fe2+)5Si8O22(OH)2 
Availability
Sold
Size
6.5 x 5.5 x 3 cm - Sm Cabinet 

Actinolite is a metamorphic mineral characteristic of greenschist facies. It is typically green, and this color is an uncommon bright green.


Actinolite

Formula
Ca2(Mg,Fe2+)5Si8O22(OH)2 
Crystal System
Monoclinic 
Crystal Habit
Bladed, Radial, Fibrous 
Cleavage
Perfect, Perfect, None 
Luster
Vitreous (Glassy) 
Color
green, green black, gray green, black 
Streak
white 
Class
Monoclinic - Prismatic 
Fracture
Splintery 
Hardness
5.5 
Collection
Phillips Collection

Almandine

#PD42423
Locality
South Tunnel Gotthard, Switzerland 
Formula
Fe2+3Al2(SiO4)3 
Availability
Sold
Size
7.5 x 6 x 5 cm - Sm Cabinet 

Red Almandine garnets to 1.5cm.


Almandine

Formula
Fe2+3Al2(SiO4)3 
Crystal System
Isometric 
Crystal Habit
Equant crystals, rounded grains, typically well-formed dodecahedra or trapezohedra 
Cleavage
None 
Luster
Vitreous - Resinous 
Color
brown, brownish red, red, black, black red 
Streak
white 
Class
Isometric - Hexoctahedral 
Fracture
Brittle - Conchoidal 
Hardness
7-8 
Collection
Phillips Collection
Mineralpedia
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Almandine

#PD42425
Locality
Arendal, Aust-Agder, Norway 
Formula
Fe2+3Al2(SiO4)3 
Availability
Sold
Size
6 x 5 x 3 cm - Sm Cabinet 

Nice Almandine garnets to 2cm in schists.


Almandine

Formula
Fe2+3Al2(SiO4)3 
Crystal System
Isometric 
Crystal Habit
Equant crystals, rounded grains, typically well-formed dodecahedra or trapezohedra 
Cleavage
None 
Luster
Vitreous - Resinous 
Color
brown, brownish red, red, black, black red 
Streak
white 
Class
Isometric - Hexoctahedral 
Fracture
Brittle - Conchoidal 
Hardness
7-8 
Collection
Phillips Collection
Mineralpedia
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On Dakota Matrix
Previously Sold Almandine
On Dakota Matrix
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Mindat
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Andalusite

#PD41533
Locality
Champion mine, Marquette Co., Michigan, United States 
Formula
Al2OSiO4 
Availability
Sold
Size
12 x 7 x 4.5 cm - Cabinet 

Flesh colored pink crystals to 2cm in quartz matrix. Andalusite typically crystallizes with square cross-sections like these crystals. Occurs in low pressure and low to high temperature metamorphosed rock rich in aluminum.


Andalusite

Formula
Al2OSiO4 
Crystal System
Orthorhombic 
Crystal Habit
Blocky, Prismatic, Euhedral Crystals 
Cleavage
Distinct, Indistinct, Poor 
Luster
Vitreous (Glassy) 
Color
dark green, gray, brown, red, green 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Splintery 
Hardness
6.5-7 
Collection
Phillips Collection

Andalusite

var. chiastolite - #42428
Locality
Coldwater Canyon, Santa Monica Mts, Los Angeles Co., California, United States 
Formula
Al2OSiO4 
Availability
Sold
Size
2 x 2 x 1 cm - Thumbnail 

Seven (two not shown) cut Andalusite section exhibiting cruciform patterns of carbonaceous inclusions.


Andalusite

Formula
Al2OSiO4 
Crystal System
Orthorhombic 
Crystal Habit
Blocky, Prismatic, Euhedral Crystals 
Cleavage
Distinct, Indistinct, Poor 
Luster
Vitreous (Glassy) 
Color
dark green, gray, brown, red, green 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Splintery 
Hardness
6.5-7 
Collection
Eaton Collection

Andradite

#37723
Locality
Homestake mine, Lawrence Co., South Dakota, United States 
Formula
Ca3Fe3+2(SiO4)3 
Availability
Sold
Size
2 x 2 x 2 cm - Thumbnail 

Two crude Andradite crystals from famous Homestake mine.


Andradite

Formula
Ca3Fe3+2(SiO4)3 
Crystal System
Isometric 
Crystal Habit
Crystalline - Coarse, Euhedral Crystals, Massive 
Cleavage
None, None, None 
Luster
Vitreous (Glassy) 
Color
black, yellowish brown, red, greenish yellow, gray 
Streak
white 
Class
Isometric - Hexoctahedral 
Fracture
Conchoidal 
Hardness
6.5-7 
Mineralpedia
View Andradite
On Dakota Matrix
Previously Sold Andradite
On Dakota Matrix
Other Available Andradite
WebMineral
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Mindat
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