$75Median
9Sold (12 mo)
$250Last sale
Colemanite specimens for sale
5 for sale · $80–$300 USD
103 in the gallery
Colemanite is a hydrated calcium borate mineral that typically forms as colorless to pale crystals with a vitreous to subadamantine luster. It often occurs in soft, tabular crystals or granular masses, and can display a translucent to near-transparent appearance when well-formed. The mineral is commonly associated with evaporite environments and is frequently found in borate-rich deposits, including reduced or alkaline settings that favor boron-bearing minerals. Notable specimens have been recovered from localities in Turkey and the United States, where Colemanite can appear in sizeable crystals or compact aggregates that reflect light well and show clean, glassy faces.
- Formula
- Ca[B3O4(OH)3] · H2O
- Rarity
- Common
- Stability
- Moderately Stable
- Collector interest
- Moderate Interest
- Classification notes
- Borate; hydrated hydroxyl calcium borate, Strunz 6.CB
Key characteristics
- Crystal system
- monoclinic
- Mohs hardness
- 4.5
- Specific gravity
- 2.42
- Luster
- vitreous
- Transparency
- transparent, translucent
- Color
- colorless, white, gray, yellow
- Streak
- white
- Cleavage
- perfect
- Fracture
- subconchoidal, uneven
- Crystal habit
- prismatic, equant, granular, massive
- Gem mineral
- Fluorescent: white, yellow
- Classic / historic
Buy Colemanite specimens
View all 5Where Colemanite is found
Top localities
- Boron10 specimens
- Thompson Mine3 specimens
- Death Valley2 specimens
- Türkiye1 specimen
- Hisarcik Mine1 specimen
- San Bernardino County1 specimen
- Turkey1 specimen
- Baker Mine1 specimen
About Colemanite
Collectors prize Colemanite for its delicate hue and the way crystals sometimes form striking, elongated prisms or prismatic stacks. Its occurrence alongside other borates can produce visually appealing combinations, and the mineral’s relatively soft, easy cleavage adds to its display appeal when safely prepared. While not among the hardest minerals, Colemanite’s rarity in certain localities and its bright, glassy appearance make it a sought-after piece for garnet-like collections or evaporite-themed displays.
