Mineral description : Goethite

Goethite from Finnish Lapland.

Mineral class	Oxides : Goethite - lepidokrokite group
Chemical formula	FeO(OH)
Crystal system	Orthorombic
Habitus	Prismatic crystals. Occurs often as tabular, needle like, botryidal or stalactitic aggregates. Also as earthy, amorph or porous masses.
Cleavage	Perfect, greasy feeling.
Hardness	5-5.5
Density	4.3
Color	Nuances from black, brown to brownish yellow.
Streak	Brownish yellow.
Luster
Description
Occurance	Created by oxidation of pyrite and other iron ores.
Associates
Notes	The main ingredience in limonite.
Locations	A very common mineral in Sweden. Mossgruvan, Grängesberg. In lake sediments and in swamps. Pottäng Baryte mine, Alnön, Sundsvall. As brown reniform aggregates. Stollgruvan, V Silberg, Ludvika. As brownish black shiny aggregates. Gladhammargruvan. As small redbrown goethite crystals in quartz.

To oxides index.

Mineral group index.

Main index.

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