Howlite: The White Borate Stone Behind Most Fake Turquoise

Short answer: howlite is a soft, white calcium borosilicate, Ca2B5SiO9(OH)5, that forms as chalky nodules in dry-lake borate deposits, most famously in southern California. It rates about 3 to 3.5 on the Mohs scale, usually carries gray to black veins, and is porous enough to take dye easily. That is why so much "turquoise" in tourist jewelry is really blue-dyed howlite.

Where does howlite come from?

Howlite is a desert mineral. It grows in borate evaporite beds: the salt-and-clay layers left behind when lakes in closed basins dried out and concentrated boron from volcanic springs and runoff. Minerals.net lists its common companions as borax, ulexite, colemanite and anhydrite, the same suite mined for industrial borates.

California is the classic source. Minerals.net names Tick Canyon (near Saugus), Lang, Los Angeles Co.; Daggett, San Bernardino Co.; Death Valley, Inyo Co.; and Boron, in the Kramer District, where the nodules can be enormous. The International Gem Society describes California nodules up to a weight of several hundred pounds, as at Lang in Los Angeles County. Smaller occurrences include the Muddy Mountains in Nevada and the Bigadiç borate mines in Turkey.

The mineral was first described from Nova Scotia, Canada. Webmineral records that it was named after Henry How of Nova Scotia when he first described it in 1868. How was a chemist and mineralogist working on the gypsum and borate beds around Windsor, and the Canadian occurrences remain important to collectors for one reason: according to Minerals.net, the Nova Scotia localities near Windsor and at Bras d'Or Lake on Cape Breton Island are the only places where visibly crystallized howlite has been found, as tiny tabular crystals on large nodules.

What is howlite, chemically and physically?

Howlite is a hydrous calcium borosilicate. By weight, boron makes up 13.81 percent of the ideal formula, which is a lot for a common ornamental stone and explains why howlite turns up wherever borax is mined.

What do howlite nodules look like?

Raw nodules are lumpy white masses that, in Minerals.net's description, often resemble cauliflower heads. Cut one open and the interior is fine-grained, opaque and chalky white, crossed by a net of thin gray, brown or black lines. Those lines are the selling point and the giveaway at the same time: they look like the matrix in spiderweb turquoise, which is exactly why dyers chose howlite.

Does howlite fluoresce?

Sometimes, and the reported colors vary by source and locality. Webmineral lists a bright sky blue glow under longwave ultraviolet light. The International Gem Society reports brownish yellow in shortwave UV, and some California material deep orange in longwave. Minerals.net says it may fluoresce cream-yellow to white in shortwave. Treat fluorescence as a supporting clue, not a test, and expect dyed material to behave differently from untreated white stone.

Why is howlite dyed to look like turquoise?

Three properties make it a convenient blank: it is white, it is porous, and it is cheap. The International Gem Society puts it bluntly: howlite is frequently dyed blue to resemble turquoise, and it makes a most convincing simulant. Minerals.net goes further, warning that some dishonest dealers label dyed howlite as turquoise without disclosing it. On its turquoise page, Minerals.net adds that other materials, especially white howlite and chalcedony, are occasionally dyed blue as an artificial simulant.

Honest sellers use names such as "dyed howlite" or "howlite, dyed blue". Names that blur the line include "turquenite", "blue howlite" without the word dyed, or "turquoise" with a price far below what real turquoise of that size costs. The planned guide to dyed howlite sold as turquoise covers labeling in more depth, and dyed stones covers dye treatments in general.

Magnesite: the other white blank

Magnesite is the second white stone used the same way. It is a magnesium carbonate, often veined with black or brown, polished into beads and spheres, and dyed in the same colors. It is denser than howlite (specific gravity 3.0 to 3.3 against howlite's 2.45 to 2.58) and a little harder. Its porous masses even adhere to the tongue when licked, which says a great deal about how readily it soaks up dye.

How can you tell dyed howlite from turquoise?

None of these checks is a lab test, but together they catch most dyed howlite:

1. Look into the cracks with a 10x loupe. Dye collects in fractures and pores, so color is darker along veins and pits. Natural turquoise color runs through the stone, not along its seams.
2. Check the veins. On howlite the dark lines are thin, gray to black and sharply drawn on the white base. Turquoise matrix is usually brown, tan or black and sits as a web or patches, often slightly recessed.
3. Weigh it if you can. Turquoise has a specific gravity of 2.6 to 2.8; howlite is lighter, magnesite heavier. A careful hydrostatic weighing can separate them.
4. Compare hardness indirectly. Turquoise rates 5 to 6; howlite only 3 to 3.5. Worn, rounded facet edges and fine surface scratches on a bead are more typical of the softer stone. Never scratch a piece you have not bought.
5. Swab an inconspicuous spot. A cotton swab with acetone or nail polish remover may pick up blue from cheaply dyed stones. Ask the seller first; it can damage a stabilized coating.
6. Read the price. Blue stone sold by the strand for a few dollars is almost never natural turquoise.

Minerals.net also notes that howlite is soluble in hydrochloric acid, which is how a lab or a careful mineralogist would confirm it on rough material, not something to try on jewelry.

Is undyed white howlite worth buying?

As a mineral, yes, cheaply. White howlite is an honest ornamental stone with a strong, graphic look: white ground, dark veins, smooth matte polish. The International Gem Society notes that spheres up to about 8 inches in diameter have been cut, along with cabochons and tumbled stones. Collectors of borate minerals often want a California nodule alongside ulexite and colemanite from the same mines. In crystal traditions howlite is associated with patience and calm study; that belongs to folklore, not to the mineral's properties.

Caring for howlite

At Mohs 3 to 3.5 howlite scratches easily, so store it apart from quartz and other hard crystals. Its porosity means it absorbs oils, lotions and dyes, which can stain white stone permanently. Wipe it with a dry or barely damp cloth, avoid soaking, and keep dyed pieces out of strong sunlight, since some dyes fade.

What to look for when you buy howlite

For white howlite, look for a clean, bright white ground with crisp, even veining, a smooth polish without pits, and no yellowing from handling oils. For dyed howlite, the label should say dyed. Price should reflect a common, soft ornamental stone: inexpensive per piece, with spheres and carvings priced for the work, not the material.

From the howlite in stock:

• White howlite, small pieces: the low-cost way to see the natural white and gray veining before any dye is involved.
• White howlite, larger piece: a bigger stone where the vein pattern has room to show; check the photos for pitting and an even white ground.

If what you actually want is a naturally blue stone rather than a dyed one, compare with genuine lapis lazuli:

• Deep blue lapis lazuli obelisk from Afghanistan: its blue comes from lazurite throughout the rock, with white calcite and gold pyrite flecks, the opposite of dye pooled in cracks. The lapis vs sodalite comparison explains how to judge it.

Frequently asked questions

Is howlite a real stone or man-made?

Howlite is a real, natural mineral, a calcium borosilicate first described in 1868 from Nova Scotia and mined in large nodules in California borate deposits. What is artificial is the color when it is sold blue: that is dye, applied because the white stone is porous.

How do you know if turquoise is really dyed howlite?

Look for dye concentrated in cracks and along veins under a loupe, thin black veins on a white base where chips show, a light feel in the hand, and a price far below real turquoise. A lab can confirm it with specific gravity, refractive index and chemistry.

Is howlite expensive?

No. Howlite is abundant and easy to acquire, so white tumbled stones and beads cost very little. Large spheres and carvings cost more for the cutting work. A high price for dyed howlite labeled as turquoise is the real risk to a buyer.

Can howlite go in water?

Brief rinsing will not dissolve it, but howlite is porous and soft, so avoid soaking it, salt water and cleaning chemicals. Dyed pieces may bleed color. Wipe it clean with a soft cloth instead.

Why does howlite have black lines?

The gray to black lines are thin veins of other material running through the fine-grained white howlite nodule. They give the stone its graphic look and are why dyed howlite imitates spiderweb turquoise so well.

Sources

• Webmineral, Howlite Mineral Data: https://webmineral.com/data/Howlite.shtml
• Minerals.net, Howlite: https://www.minerals.net/mineral/howlite.aspx
• International Gem Society, Howlite Value, Price, and Jewelry Information: https://www.gemsociety.org/article/howlite-jewelry-and-gemstone-information/
• Minerals.net, Turquoise gemstone: https://www.minerals.net/gemstone/turquoise_gemstone.aspx
• Minerals.net, Magnesite: https://www.minerals.net/mineral/magnesite.aspx
• Minerals.net, Ulexite: https://www.minerals.net/mineral/ulexite.aspx