What Is Howlite? The Stone Often Sold as Turquoise

Howlite is a calcium borosilicate hydroxide mineral, naturally white to grey, patterned with fine grey-to-black veining. It was first described in Nova Scotia, Canada, in 1868 by geologist Henry How, who the mineral is named after.

Why It Forms This Way

Howlite typically forms in evaporite deposits — sedimentary environments where mineral-rich water has evaporated, concentrating dissolved minerals into deposits, often alongside borate and gypsum minerals. It commonly occurs as irregular, cauliflower-like nodules rather than well-formed crystals.

Why It Takes Dye So Well

Howlite's structure is porous enough to readily absorb dye, and its naturally occurring grey-black veining closely resembles the matrix pattern seen in turquoise — a combination that makes it an easy, low-cost material to dye blue and market as "turquoise howlite" or, less scrupulously, simply mislabeled as turquoise. It's also commonly dyed other colors (including deep blue to imitate lapis lazuli, and various bright shades) precisely because of how evenly and cheaply it accepts color.

Spotting Dyed Howlite

Genuine, untreated howlite is white or cream-colored with grey veins — if you see it in that natural state, it hasn't been dyed. Dyed "turquoise" howlite typically shows a very uniform, saturated blue-green with black veining that looks slightly too regular and too dark compared to genuine turquoise's more varied, uneven matrix; it's also priced far below real turquoise, which is a practical tell on its own.

Where It's Mined

Nova Scotia and California are the primary sources.

Quick Facts

Mineral family: calcium borosilicate hydroxide — Hardness: 3.5 on the Mohs scale (notably soft) — Naturally white/grey — Frequently dyed to imitate turquoise or lapis lazuli — Major sources: Nova Scotia, California.