Sursassite
Current inventory:  0 gems
 

  
Sursassite is named from the Roman name for Oberhalbstein, now Sursass, Switzerland which is the type locality.

Discovered in 1926;   IMA status:  Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Mn²⁺₂Al₃(SiO₄)(Si₂O₇)(OH)₃

Manganese Aluminum Silicate Hydroxide

Molecular Weight:

502.09 gm

Composition:

Manganese

21.88 %

Mn

28.26 %

MnO

Aluminum

16.12 %

Al

30.46 %

Al₂O₃

Silicon

16.78 %

Si

35.90 %

SiO₂

Hydrogen

0.60 %

H

5.38 %

H₂O

Oxygen

44.61 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/C.24-20

Nickel-Strunz 10th Ed. ID:

9.BG.15

9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO₄ and Si₂O₇ groups; cations in octahedral [6] and greater coordination

Related to:

None

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As fibers, up to 2.5 cm, in veinlets and as radiated botryoidal masses.

Twinning:

None

Physical Properties

Cleavage:

Distinct on {101}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

n/a

Density:

3.256 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Red-Brown to Copper-Red

Transparency:

Translucent

Luster:

Silky, Dull

Refractive Index:

1.736 - 1.766  Biaxial  ( - )

Birefringence:

0.030

Dispersion:

Strong; r > v

Pleochroism:

Strong; X = Z = colorless to pale yellow; Y = deep golden brown

Occurances

Geological Setting:

As vein fillings in manganese deposits in low-grade metasediments.

Common Associations:

Braunite, Barite, Calcite, Quartz

Common Impurities:

Ti, Fe, Mg, Ca, Na, K, H₂O

Type Locality:

Parsettens Alp, Tinizong (Tinzen), Oberhalbstein (Surses; Sursass), Albula Valley, Grischun (Grisons; Graubünden), Switzerland

Year Discovered:

1926

View mineral photos:

Sursassite Mineral Photos and Locations

More Information

Mindat.org 
Webmineral.com

Sursassite is a rare manganese silicate mineral found at only a few localities around the world. Crystals are found as red-brown to copper-red fibers or botryoidal masses in veinlets. Sursassite has strong dispersion and pleochroism. Material from the Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy is rarely available as cabochons.

Sursassite is found in just a few locations around the world. From the Val d'Err, Oberhalbstein, GraubÄunden, Switzerland. In the Plymouth deposit, near Woodstock, New Brunswick, Canada. From the Palos Verdes Hills, Los Angeles County, California, USA. In the Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy. On Andros Island, Cyclades Islands, Greece.
 

  
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