mineral

White Howlite

Howlite (Calcium borosilicate hydroxide, Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Milky white to light grey with grey or black spider-web veining; Lustre: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None/Indistinct; Specific Gravity: 2.53–2.59.

Hardness: 3

Identified March 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits within continental basins. It is found in sedimentary environments where boron-rich volcanic waters have reacted with calcium-rich sediments. It does not have a specific 'geological age' as it forms across many eras depending on local basin activity.

Uses & applications

Used primarily in lapidary work for carvings, beads, and cabochons. Because of its porous nature, it is frequently dyed blue to imitate turquoise or red to imitate coral. It is also used as a source of borate in industrial applications.

Geological facts

First discovered in 1868 by Henry How in Nova Scotia, Canada. It is often sold under the trade names 'White Turquoise' or 'Buffalo Turquoise,' although it is geologically unrelated to true turquoise.

Field identification & locations

Identify by its opaque white color and characteristic erratic grey veins. In the field, look for cauliflower-like nodules. It is softer than quartz (which it can resemble), meaning it can be scratched by a steel copper penny or knife. Found commonly in California (USA) and Nova Scotia (Canada).

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