Milarite
Mineral (K,Na)Ca2AlBe2Si12O30·H2O
About it
Glassy six-sided prisms, colourless to pale green, from pegmatites and Alpine clefts; bright yellow-green crystals come from Guanajuato, Mexico.
- Type
- Mineral
- Group
- Silicate (cyclosilicate), milarite group
- Formula
- (K,Na)Ca2AlBe2Si12O30·H2O
- Hardness (Mohs)
- 5.5–6
- Specific gravity
- 2.46–2.61
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Hexagonal
- Colours
- colourless, yellow-green, green, yellow, tan
- Transparency
- transparent, translucent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.