Jarosite
Mineral KFe3(SO4)2(OH)6
About it
Yellow-brown crusts and tiny glittering rhombs that form where pyrite weathers in acid conditions. Named for the Barranco del Jaroso in Spain, and detected on Mars by the Opportunity rover.
- Type
- Mineral
- Group
- Sulfate, alunite group
- Formula
- KFe3(SO4)2(OH)6
- Hardness (Mohs)
- 2.5–3.5
- Specific gravity
- 2.9–3.26
- Streak
- pale yellow
- Lustre
- vitreous (glassy), resinous, earthy
- Crystal system
- Trigonal
- Colours
- amber yellow, yellowish brown, golden brown
- Transparency
- translucent, opaque
- Cleavage and fracture
- distinct basal; uneven fracture
Typical values: real specimens vary. For more, see mindat.org.