mineral

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

AI-generated identification · may be incorrect

Hardness: 3.5 on Mohs scale; Color: White or milky grey with dark brown or black web-like veins; Luster: Sub-vitreous to pearly; Crystal structure: Monoclinic; Cleavage: None; Specific gravity: 2.53–2.59

Hardness: 3
Color: White or milky grey with dark brown or black web-like veins
Luster: Sub-vitreous to pearly

Identified March 15, 2026More mineral →

Explore Howlite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in evaporite deposits within sedimentary basins through the precipitation of calcium and boron. Most significant deposits range from the Miocene to Holocene epochs.

Uses & applications

Used primarily for jewelry (cabochons and beads) and decorative carvings. It is often dyed to imitate turquoise or lapis lazuli due to its porous nature.

Geological facts

First discovered by Henry How in 1868 near Windsor, Nova Scotia. In the metaphysical community, it is colloquially known as the 'white turquoise' or 'calming stone.'

Field identification & locations

Identify in the field by its distinct irregular, 'spider-web' dark veins against a porcelain-like white surface. It is commonly found in Tick Canyon, California, and various sites in Nova Scotia, Canada.