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Tschermakite  
Current inventory:  0 gems
 

Tschermakite

  
Tschermakite was named to honor Professor Gustav Tschermak von Seysenegg (1836-1927), Austrian mineralogist, University of Vienna, Vienna, Austria.

Discovered in 1945.   IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

Ca2Mg3Al3Fe3+Si6O22(OH)2

 

Calcium Magnesium Aluminum Iron Silicate Hydroxide

Molecular Weight:

844.38 gm

Composition:

Calcium

9.49 %

Ca

13.28 %

CaO

 

Magnesium

8.64 %

Mg

14.32 %

MgO

 

Aluminum

9.59 %

Al

18.11 %

Al2O3

 

Iron

6.61 %

Fe

9.46 %

Fe2O3

 

Silicon

19.96 %

Si

42.69 %

SiO2

 

Hydrogen

0.24 %

H

2.13 %

H2O

 

Oxygen

45.48 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.10-60

Nickel-Strunz 10th Ed. ID:

9.DE.10

 

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si
4O11; Clinoamphiboles

Related to:

Amphibole Group. Calcic Clino-Amphibole Subgroup. Tschermakite - Ferrotschermakite Series.

Synonyms:

Tschermakitic hornblende, Aluminotschermakite

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As prismatic crystals; as reaction rims on other minerals.

Twinning:

Simple or multiple twinning || {100}.

 

 

Physical Properties

   

 

Cleavage:

Perfect on {110}, intersecting at 56º and 124º; partings on {100}, {001}.

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

3.15 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Medium Green to dark Green to Green-Black to Black, Brown (rare).

Transparency:

Transparent to Opaque

Luster:

Vitreous

Refractive Index:

1.68 - 1.698  Biaxial ( + ) or ( - )

Birefringence:

0.0180

Dispersion:

Strong; r > v

Pleochroism:

Visible to Distinct; in greens and browns

 

 

Occurances

   

   

Geological Setting:

From eclogites and other ultramafic igneous rocks, and in medium- to high-grade metamorphic rocks, typically amphibolites.

Common Associations:

Kyanite, Garnet

Common Impurities:

Ti, Mn, Na, K, H2O

Type Locality:

(possibly Bamle, Norway)

Year Discovered:

1945

View mineral photos:

Tschermakite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Tschermakite is a fairly common but rarely identified mineral. It often occurs in association with massive green
Zoisite and Ruby at the Mundarara Mine,  Longido, Mt. Kilimanjaro, Kilimanjaro Region of Tanzania. Black inclusions of Tschermakite are frequently seen in attractive cabochons of bright green Zoisite and pinkish-red Ruby.

Probably widespread. Well-studied material from: Hurry Inlet, Fiskenæsset, Greenland. At Glenelg and Knockormal, Ayrshire, Scotland. From Lake Kutemajärvi, Orivesi, and Perniö, Finland. In France, from Le Viala du Tarn, Aveyron. From the central Bug region, Ukraine.
 

  
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