Laumontite
Mineral CaAl2Si4O12·4H2O
Also called Leonhardite
Take care.
- Fragile: Handle it gently and pack it well; it breaks or crumbles easily.
About it
Square prisms with slanted ends that lose water in dry air and crumble to chalky powder, so collectors often seal them. Common in veins and cavities in altered volcanic rock.
- Type
- Mineral
- Group
- Silicate (tectosilicate), zeolite group
- Formula
- CaAl2Si4O12·4H2O
- Hardness (Mohs)
- 3–4
- Specific gravity
- 2.23–2.41
- Streak
- white
- Lustre
- vitreous (glassy), pearly
- Crystal system
- Monoclinic
- Colours
- white, grey, pink, cream, brown
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in two directions
Typical values: real specimens vary. For more, see mindat.org.