Siderite

Real mineral · common · Fe++CO₃

Iron carbonate, an ore worked since the Iron Age and a common cement in sedimentary rock. Its curved rhombohedra tarnish from honey brown to near black as the iron oxidises at the surface.

Identity

Formula

Fe++CO₃

Chemical class

carbonate

Mineral group

Calcite, Rhodochrosite, Smithsonite

Also known as

Chalybite, Spathic iron

Crystallography

Crystal system

trigonal

Habits

rhombohedral, botryoidal, massive, granular

Fracture

conchoidal

Physical properties

Mohs hardness

3.5

Density

3.96 g/cm³

Luster

vitreous

Colors

yellowish brown, brown, gray, yellowish gray, greenish gray

Streak

white

Transparency

translucent

Geology

Origins

sedimentary, hydrothermal

Host rocks

shale, ironstone, vein

Associated minerals

Pyrite, Calcite, Quartz, Galena

Geography

United Kingdom, Germany, Bolivia

Classification

Rarity

common

Gem quality

No

Browse the Crystal Encyclopedia — MGS Toolbox