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Richterite
Current inventory:  0 gems
 

Chemistry:  Na(CaNa)(Mg,Fe2+)₅[Si₈O₂₂](OH)₂  
[Sodium Calcium Magnesium Iron Silicate Hydroxide]

Discovered in 1865;   IMA status: Valid (pre-IMA; Grandfathered).
Richterite is named after Theodor Richter (1824 - 1898), a German mineralogist.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/F.09-10

Nickel-Strunz 10th Ed. ID:

9.DE.20

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si₄O₁₁; Clinoamphiboles

Related to:

Amphibole Group. Sodic - Calcic Clino - Amphibole Subgroup. Ferrorichterite - Richterite Series

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Crystals commonly prismatic, flattened along [100], rarely doubly terminated, to 15 cm; acicular or asbestiform.

Twinning:

Simple or multiple twinning on [100].

Physical Properties

Cleavage:

[110] Perfect; partings on [100] and [001]

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Hardness (Mohs):

5.0 - 6.0

Density:

2.97 - 3.45 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Blue, Brown, Brown Red, Gray Violet, Yellow

Transparency:

Translucent to Transparent

Luster:

Vitreous

Refractive Index:

1.615 - 1.636  Biaxial ( - )

Birefringence:

0.0210

Dispersion:

Strong; r < v

Pleochroism:

Strong; in pale yellows, orange, and red.

Occurances

Geological Setting:

Commonly in contact metamorphosed limestones; in alkalic igneous rocks and carbonatites. Also in meteorites.

Common Associations:

Apatite, Calcite, Cristobalite, Diopside, Enstatite, Forsterite, Leucite, Natrolite, Phlogopite, Plagioclase

Common Impurities:

Ti,Al,Cr,Mn,Ni,Sr,K,F,Cl,H₂O

Type Locality:

Långban, Filipstad, Värmland, Sweden

Year Discovered:

1865

View mineral photos:

Richterite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Richterite is closely related to Tremolite. Richterite is the sodium rich version of Tremolite which is Calcium rich. Richterite is a member of the Calcic Clino-Amphibole Subgroup of the Amphibole Group of minerals that includes Actinolite, Ferro-edenite, Kaersutite, Pargasite, Richterite and Tremolite. The Amphibole Group is an extensive and complex group of minerals currently divided into several sub-groups. Richterite is usually opaque to translucent and clean, facetable crystals are very rare and small.

There are small, gemmy, yellow crystals found in Badakhshan Province, Afghanistan but these are quite rare. Richterite is also found in the meteorite field at Canyon Diablo, Arizona, USA.
 

  
Richterite gems for sale:

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