Borax
11 in the gallery
Borax is a hydrated borate mineral forming colorless to white crystals that often occur as fibrous or acicular aggregates, sometimes appearing as transparent, glassy crystals with a vitreous luster. It typically forms in evaporite environments and is associated with borate-rich systems, sometimes coating surfaces in mineral-rich springs or as crusts on evaporite beds. Classic specimens have come from arid, salt-rich locales where boron-bearing solutions crystallize, producing delicate, elongated crystals that can be prismatic or acicular in habit.
- Formula
- Na2(B4O5)(OH)4 · 8H2O
- Rarity
- Common
- Stability
- Moderately Stable
- Collector interest
- Moderate Interest
- Classification notes
- Borate minerals; Phyllosilicates? (placeholder)
Key characteristics
- Crystal system
- monoclinic
- Mohs hardness
- 2–2.5
- Specific gravity
- 1.7–1.72
- Luster
- vitreous, resinous
- Transparency
- transparent, translucent
- Color
- colorless, white, gray, yellow, green, blue
- Streak
- white
- Cleavage
- perfect
- Fracture
- conchoidal, uneven
- Crystal habit
- prismatic, massive, granular
- Classic / historic
Where Borax is found
Top localities
- Searles Lake3 specimens
- Baker Mine2 specimens
About Borax
Collectors value Borax for its clean, bright appearance and its historical significance in mineralogy and industry, as well as its association with other borates. While often found in microcrystalline forms or aggregated masses, the mineral can present a striking contrast against darker minerals in a collection. Notable specimens from well-known Borax-bearing localities attract interest for their crystallography and the way they reveal evaporite deposition processes, making them desirable for display and study.