$48Median
2Sold (12 mo)
$45Last sale
Ulexite specimens for sale
1 for sale · $160 USD
31 in the gallery
Ulexite is a borate mineral that forms as transparent to opaque white to colorless nodules and fibrous aggregates. It has a pearly to vitreous luster and often displays a silky or silky-melted appearance, characteristic of its fuzzy, fibrous habit. The mineral is renowned for its unique internal transparency, which allows light to pass through layers and produce a natural image on the opposite surface, a phenomenon known as satiny bituminite in some descriptions.
- Formula
- NaCa[B5O6(OH)6] · 5H2O
- Rarity
- Common
- Stability
- Moderately Stable
- Collector interest
- Very High Interest
- Classification notes
- Borates; hydrated borates (Strunz 6.BA)
Key characteristics
- Crystal system
- triclinic
- Mohs hardness
- 2.5
- Specific gravity
- 1.95–1.96
- Luster
- vitreous, silky
- Transparency
- transparent, translucent
- Color
- colorless, white, gray
- Streak
- white
- Cleavage
- perfect
- Fracture
- uneven
- Crystal habit
- acicular, fibrous, radiating, massive
- Gem mineral
- Fluorescent: white, yellow, green
- Classic / historic
Buy Ulexite specimens
View all 1Where Ulexite is found
Top localities
- Boron12 specimens
- West Baker Mine2 specimens
- Arequipa1 specimen
- Baker Mine1 specimen
About Ulexite
Notable localities include several U.S. mines and Peruvian exposures that yield lustrous, well-formed specimens. Collectors prize the soft texture, the striking optical effect, and the way surface polish reveals ghost-like images within the stone. Ulexite tends to form in evaporitic environments and commonly occurs in rolled fibers or blob-like masses that can be cut and prepared for display, highlighting its distinctive interior glow.
