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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axelsson@acc.umu.se
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Last changed : 1998-03-07