Howlite

Howlite is a white to gray calcium borosilicate mineral, easily recognized by its marble-like white body crossed by dark gray to black spiderweb veining. It usually occurs as compact, porous nodular masses rather than visible crystals.

Because it is porous and takes dye exceptionally well, howlite is very commonly dyed blue to imitate turquoise (sometimes sold as turquenite or white turquoise) and dyed in other colors as well. In its natural state its white-and-veined look is attractive in its own right.

Named after the Canadian chemist Henry How, who described it in 1868, howlite is a soft, affordable lapidary material.

Howlite forms as a secondary borate mineral in evaporite deposits, precipitating from boron-rich solutions in association with other borates like borax and ulexite. It typically develops as nodules and irregular masses in sedimentary borate beds.

These conditions occur in arid regions with ancient evaporated lakes and playas. The most important deposits are in California and other parts of the western USA, with additional occurrences in Canada (Nova Scotia, the type locality), Mexico, Turkey and Russia.

Howlite is white to gray with characteristic dark gray-black veining and a chalky, porous, dull-to-subvitreous appearance. It is soft (hardness 3.5), easily scratched by a knife, with a white streak. It is light in weight and can be slightly absorbent.

Look-alikes: Magnesite is very similar (white with veining) but slightly harder and reacts to acid; howlite does not effervesce readily. Dyed howlite is the famous turquoise imitation, distinguishable because true turquoise is harder (5-6) and the dye in howlite often concentrates in the veins. White marble and kaolinite can also resemble it. Softness plus spiderweb veining flags howlite.

Howlite is widely used for beads, cabochons, tumbled stones and carvings, both in its natural white-veined form and, very commonly, dyed to imitate turquoise, lapis, coral and other stones. It is inexpensive and easy to carve and polish.

Its main value is as an affordable ornamental and imitation gem material. Buyers should be aware that much blue howlite is sold misleadingly as turquoise.

Metaphysically it is marketed as a calming, stress-relieving stone associated with patience and sleep, though these claims are not scientifically supported.