mineral

Howlite

Howlite (Ca2B5SiO9(OH)5)

Hardness: 3.5 on Mohs scale; Color: Opaque white or milky white with erratic grey or black veining; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic (usually found in massive/nodular form); Specific Gravity: 2.45-2.58.

Hardness: 3
Luster: Sub-vitreous to pearly

Identified June 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed in evaporite deposits, usually as nodules in sedimentary basins. It is a calcium borosilicate hydroxide mineral often found in continental saline environments through the precipitation of boron-rich waters.

Uses & applications

Primarily used for beads, cabochons, and decorative carvings. Due to its porous nature, it is frequently dyed blue to imitate turquoise or red to imitate coral. Used in jewelry and by collectors.

Geological facts

First discovered in 1868 by Henry How near Windsor, Nova Scotia. It is naturally very porous, which is why it is the most common substitute for turquoise when dyed. In its natural white state, it is sometimes called 'White Buffalo Stone' or 'White Turquoise'.

Field identification & locations

Identified by its cauliflower-like habit in the wild and its distinct web-like dark veining. It is softer than quartz and can be scratched by a steel needle. Frequently found in California (USA) and Nova Scotia (Canada).