mineral

White Howlite

Howlite (Hydrated calcium borosilicate, Ca2B5SiO9(OH)5)

Hardness: 3.5 on the Mohs scale. Color: White or milky-white with distinctive dark grey, black, or dark brown web-like veins (matrix). Luster: Vitreous to sub-vitreous, often dull when tumbled. Crystal structure: Monoclinic, though crystals are extremely rare; typically found in massive, nodular form. Cleavage: None.…

Hardness: 3
Luster: Vitreous to sub-vitreous, often dull when tumbled

Identified July 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms in evaporite deposits, typically in borate minerals found in lacustrine (lake) environments. Often occurs in irregular nodules or cauliflower-like masses in sedimentary rock strata.

Uses & applications

Commonly used in tumbled stones, cabochons, beads, and carved ornaments. Frequently dyed a vivid blue or green to imitate turquoise (often called 'turquenite'), and used in costume jewelry.

Geological facts

Howlite was discovered in Nova Scotia, Canada, in 1868 by Henry How, a Canadian chemist, geologist, and mineralogist. Because it is relatively soft and porous, it readily absorbs dyes, making it one of the most commonly color-enhanced minerals in the gem trade.

Field identification & locations

Easily identified by its characteristic chalky white-to-grey color combined with dark web-like matrix lines. Its softness (can be scratched easily with a copper penny or knife) helps distinguish it from harder white stones like quartz or feldspar. Found notably in Canada, the USA (California), Germany, and South Africa.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

sedimentary

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

mineral

Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral