Siderite
Chemical Formula	FeCO3
Species	Carbonates
Crystal System	Trigonal
Mohs Scale	3-4
Specific Gravity	3.96
Color	Pale yellow to tannish, grey, brown, green, red, black and sometimes nearly colorless
Streak	White
Luster	Vitreous, Silky, Pearly
Refractive Index	n = 1.875 n = 1.633
Diaphaneity	Translucent
Cleavage	PerfectPerfect on .
Fracture	Irregular/Uneven, Conchoidal
Crystal Habit：Tabular crystals, often curved - botryoidal to massive
Geological Setting：Most often found in bedded sedimentary deposits with a biological component, with shales, clays and coal beds - suggesting that the siderite is biogenically created under low-oxygen and low-Ph conditions. It is also found in metamorphosed sedimentary rocks as more massively crystalline material, as a primary gangue mineral in hydrothermal deposits, and in pegmatites, including nepheline syenite pegamtites; as bog deposits.