Alunogen
Mineral Al2(SO4)3·17H2O
Also called Hair salt
Take care.
- Damaged by water: Keep it dry: don't wash it, and keep it out of damp places.
- Breaks down in damp air: Keep it dry and in steady humidity; some crumble or rot as they take on moisture.
About it
White fibrous crusts and efflorescences that form in mines, burning coal dumps, and around volcanic vents. Soluble in water and easily damaged by damp air.
- Type
- Mineral
- Group
- Sulfate, hydrated
- Formula
- Al2(SO4)3·17H2O
- Hardness (Mohs)
- 1.5–2
- Specific gravity
- 1.72–1.78
- Streak
- white
- Lustre
- vitreous (glassy), silky
- Crystal system
- Triclinic
- Colours
- white, colourless, yellowish, reddish
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in one direction; usually fibrous crusts
Typical values: real specimens vary. For more, see mindat.org.