Photo: Didier Descouens · CC BY-SA 3.0

Phyllosilicate mineral; polytypes: 1M, 1T, 2H2, 3T, 6R2, 6T2

Properties

Chemical formula

Fe²⁺₂Fe³⁺((Si,Fe³⁺)₂O₅)(OH)₄

Group

Silicates

Crystal system

—

Hardness (Mohs)

—

Color

Black

Luster

—

Streak

—

Density

—

Cleavage

—

Fracture

—

Tenacity

—

Crystal habit

—

Transparency

—

Space group

—

Fluorescence

—

Magnetism

—

Radioactivity

—

Refractive index

—

Optical character

—

Birefringence

—

Pleochroism

—

Strunz classification

9.ED.15

Dana classification

71.1.4.7

IMA status

Grandfathered mineral (G)

IMA symbol

Cro

Locality

🇨🇿 Příbram District

Type locality

—

Discovery year

—

Source: Wikidata