Sinhalite
Mineral MgAlBO4
About it
A brown to yellowish-green gem long taken for brown peridot until it was shown to be a borate in 1952. Named for Sinhala, an old name for Sri Lanka, where most gem pebbles are found; also from Myanmar.
- Type
- Mineral
- Group
- Borate
- Formula
- MgAlBO4
- Hardness (Mohs)
- 6.5–7
- Specific gravity
- 3.47–3.5
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Orthorhombic
- Colours
- yellow-brown, greenish brown, brown, pink
- Transparency
- transparent, translucent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.