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Source Locality:Death Valley, Inyo County, California, USA
Minerals:Colemanite 10 × 7 × 5 cm
Weight:451 grams
Description:Offered is a high-quality colemanite crystal aggregate from the classic borate deposits of Death Valley, California. The specimen consists of an intergrown cluster of approximately a dozen large, blocky colemanite crystals, with no visible matrix, allowing the crystal forms to be appreciated from all sides.
The crystals are translucent and light gray to off-white in color, with individual crystal faces ranging from approximately 1 cm up to 5 cm across. The blocky habit and substantial crystal size give the specimen strong visual presence and make it an excellent representative example of this important borate mineral. Under longwave UV these crystals produce a lantern effect. They give off white light and if you hold a UV flashlight against one side the light fills the entire specimen from the inside out (see photo).
Because the specimen lacks matrix and is composed entirely of intergrown colemanite crystals, it presents as a self-supporting crystal aggregate, suitable for cabinet display or systematic collections. Under good lighting, the translucent nature of the crystals becomes especially apparent, highlighting internal reflections and crystal geometry.
This piece represents the classic appearance of Death Valley colemanite, where crystals commonly occur as large, well-formed aggregates rather than isolated single crystals.
Geologic & Mineralogical Context:Death Valley is one of the world’s most famous regions for borate minerals, including colemanite, which formed in evaporitic and hydrothermal environments within Tertiary lake beds. Colemanite crystals from this area are known for their large size, blocky habit, and translucent appearance. Matrix-free crystal aggregates of this size are increasingly uncommon.
Photos are taken under neutral lighting and represent the specimen accurately. The exact specimen shown is the one you will receive.
Shipping:Carefully packed to ensure safe arrival. Shipping is tracked and insured.
Provenance Note:
The cabinet display card used with this mineral is included. As the card indicates on the reverse, this specimen is from the lifelong private hobby collection of a retired USGS professional. The U.S. Geological Survey (USGS) does not endorse, sponsor, or certify this mineral, nor has it evaluated this listing. This is a private liquidation of independent, historically sourced worldwide specimens.
