RARE Colemanite Mineral California USA Authentic Borate Crystal Collectable Specimen

Rare Colemanite Mineral from California, USA

This listing presents a rare Colemanite mineral specimen from California, USA, a fascinating borate crystal highly valued by collectors, mineral enthusiasts, and researchers alike. Colemanite is a secondary borate mineral, typically formed in evaporite deposits where borax and other borates undergo alteration. Its distinct appearance and scientific significance make it a sought-after specimen that captures the geological richness of California’s unique mineral landscapes.

Each piece is carefully chosen for its aesthetic appeal, crystalline structure, and natural authenticity. The photographs show an example of the type of specimen you will receive, with a Certificate of Authenticity included for complete assurance.

Geological Background of Colemanite

Colemanite is a hydrated calcium borate with the chemical formula Ca₂B₆O₁₁·5H₂O. It was first discovered in the late 19th century in California and named after William Tell Coleman, a businessman who financed early borax mining operations in the state. It is often found in association with other borates such as ulexite, kernite, and borax.

Colemanite is a key mineral in understanding borate-rich evaporite environments, where it forms as a product of groundwater alteration of borax deposits. This process typically occurs in arid regions with closed-basin lakes, where repeated evaporation concentrates boron-rich waters. California’s desert basins, particularly in areas such as Death Valley and Boron, are well-known for producing high-quality specimens.

Morphological Features

This specimen of Colemanite displays the defining characteristics of the mineral:

• Crystal Habit: Often prismatic or massive, with granular or fibrous forms.

• Colour: Usually colourless, white, or pale grey, with occasional transparent zones.

• Lustre: Vitreous to earthy, depending on surface texture and quality of crystallisation.

• Cleavage and Hardness: Good cleavage and a hardness of 4.5–5 on the Mohs scale, making it relatively durable compared to other borates.

• Transparency: Ranges from transparent to translucent, with some specimens showing attractive internal reflections.

These traits make Colemanite not only a scientific mineral of importance but also an eye-catching addition to any mineral collection.

Scientific and Industrial Importance

Colemanite has been an important ore of boron, historically mined in California for use in glass, ceramics, detergents, and fertilisers. Its role as a boron source has linked it directly to industrial development, particularly in the United States. Scientifically, it provides insights into borate mineralogy and the geochemical processes of evaporite basins.

For collectors, Colemanite offers both scientific value and aesthetic appeal. Its crystal forms, subtle colouration, and historical association with early American borax mining make it a specimen of both geological and cultural interest.

Collector’s Details

• Mineral Type: Colemanite (Hydrated Calcium Borate)

• Chemical Formula: Ca₂B₆O₁₁·5H₂O

• Location: California, USA

• Crystal System: Monoclinic

• Colour: White, colourless, or pale grey

• Hardness: 4.5–5 (Mohs scale)

• Formation Environment: Evaporite deposits, formed through alteration of borax in arid basins

• Condition: 100% genuine specimen, carefully chosen and authenticated

• Sizing: Scale cube = 1cm. Full dimensions shown in the listing photographs.

Authenticity and Presentation

All of our specimens are 100% genuine and supplied with a Certificate of Authenticity. The photographs show an example of the type of Colemanite specimen you will receive. Each piece is carefully inspected to ensure it represents the natural features of this mineral and is ready to be displayed, studied, or treasured as part of a private collection.

This rare Colemanite mineral from California, USA is both a geological treasure and a historically important mineral specimen, combining natural beauty, industrial heritage, and scientific value in one unique collectable.