Probertite
4 in the gallery
Probertite is a borate mineral that crystallizes in the monoclinic system, typically forming acicular, prismatic, radiating, or fibrous habits. Crystals are colorless to white with a vitreous to silky luster, usually transparent to translucent, and it has a white streak. Notable specimens have come from classic localities that highlight its delicate, needle-like structures and pristine translucency, making it a favorite among collectors of historic mineral species.
- Formula
- NaCaB5O7(OH)4·3H2O
- Rarity
- Uncommon
- Stability
- Stable
- Collector interest
- Moderate Interest
- Classification notes
- Borates; Strunz 6.EA.15
Key characteristics
- Crystal system
- monoclinic
- Mohs hardness
- 3.5
- Specific gravity
- 2.1–2.2
- Luster
- vitreous, silky
- Transparency
- transparent, translucent
- Color
- colorless, white
- Streak
- white
- Cleavage
- perfect
- Crystal habit
- acicular, prismatic, radiating, fibrous
- Classic / historic
Where Probertite is found
Top localities
- Baker Mine1 specimen
About Probertite
Rarity is described as uncommon, and this mineral remains stable under ordinary conditions. Its Mohs hardness of 3.5, perfect cleavage, and relatively light specific gravity around 2.1–2.2 contribute to its characteristic handling and display qualities. The combination of its classic status and striking habit—often acicular or radiating—continues to attract collectors who appreciate historic borates and the gleam of fine, slender crystals.