Colemanite

Colemanite is just a gem that is unusual is maybe not particularly appealing but is really a rarity for collectors. Colemanite is a treasure that is interesting that it’s pyroelectric and piezoelectric at very low conditions. Colemanite is also fluorescent showing bright pale under that is yellow and longwave UV that can phosphoresce pale green. Gems have become difficult to facet since Colemanite is fragile and brittle with perfect cleavage in one single direction and it is really slightly soluble in water.

Colemanite is really a borate that is complex, and like other borates, it is found in playa lakes and other evaporite deposits. Colemanite can be an ore of boron and a way to obtain borax that is a cleansing agent and of good use chemical that is industrial.

Current resources of Colemanite are Yermo, Boron, Death Valley and other Ca localities, USA; Chile; and Panderma, Turkey.

Category: Inoborates
Chemical Formula: Ca2B6O11 · 5(H2O)
Hydrated Calcium Borate
Molecular Weight: 411.09 gm
Composition: Calcium 19.50 % Ca 27.28 % CaO
Boron 15.78 % B 50.81 % B2O3
Hydrogen 2.45 % H 21.91 % H2O
Oxygen 62.27 % O
  100.00 % 100.00 % = TOTAL OXIDE

 

Crystallography: Monoclinic – Prismatic
Crystal Habit: As equant to short prismatic crystals, with large and multiple terminating forms, to 30 cm; pseudorhombohedral and pseudo-octahedral; nearly 50 forms measured; cleavable massive, granular, most commonly nodular.
Twinning: None

 

Cleavage: Perfect on [010], Distinct on [001]
Fracture: Irregular/Uneven to Sub-Conchoidal
Tenacity: Brittle
Moh’s Hardness: 4.5
Density: 2.423 (g/cm3)
Luminescence: Fluorescent; bright pale yellow under SW UV and LW UV. May phosphoresce pale green.
Radioactivity: Not Radioactive
Other: Pyroelectric and Piezoelectric at very low temperatures.
Very slightly
 soluble in water (1 part in 1,100 at 20°-25°)

 

Color: Colorless, gray, gray white, yellowish white, white
Transparency: Transparent to Translucent
Luster: Vitreous to Adamantine
Refractive Index: 1.586 – 1.614  Biaxial ( + )
Birefringence: 0.0280
Dispersion: Relatively weak; r > v
Pleochroism: None