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Psilomelane
Current inventory: 0 gems
 

Chemistry:  Ba·(H₂O)Mn³⁺₅O₁₀

Discovered about 1747;   IMA status: Discredited by IMA in 1982
Psilomelane was named in 1785 from the Greek words ψιλός (psilos) meaning smooth or bald, and μέλας (melas) meaning black, in allusion to the form and color.

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/X.0-0

4 : Oxides & Hydroxides
X : Unclassified oxides
0 :

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Commonly massive, botryoidal, stalactitic and can also be found as earthy crusts or massive.

Physical Properties

Cleavage:

None

Fracture:

Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.0

Density:

4.40 - 4.72 (g/cm³)

Radioactivity:

Not Radioactive

Optical Properties

Color:

Iron Black, Dark Steel Gray

Transparency:

Opaque

Luster:

Sub-Metallic, Dull

Refractive Index:

NCalc = 2.11 - 2.26

Birefringence:

n/a

Dispersion:

n/a

Pleochroism:

None

Occurances

Geological Setting:

Psilomelane is found as a secondary mineral in the oxidized  zone of manganese deposits.

Type Locality:

n/a

Year Discovered:

1747

View mineral photos:

Psilomelane Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Psilomelane is an obsolete group name and general term for hard, black manganese (Mn) oxide minerals. Romanèchite is the primary constituent of Psilomelane, which is a mixture of minerals. Psilomelane is often layered with gray Pyrolusite creating bands of metallic gray and sub-metallic black. The material from a recent find at the Silver Crown Mine, Chihuahua, Mexico is particularily attractive with dark gray and black bands, swirls and patterns. Psilomelane is similar in appearance to Hematite, except for the swirls and patterns.
 

  
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