Howlite, a calcium borosilicate hydroxide ( Ca₂ B₅ Si O₉(O H)₅), is a

borate mineral The borate minerals are minerals which contain a borate anion group. The borate (BO3) units may be polymerised similar to the SiO4 unit of the silicate mineral class. This results in B2O5, B3O6, B2O4 anions as well as more complex structures whic ...

found in

evaporite An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...

deposits.Howlite
at Mineral Galleries

History

Howlite was discovered near

Windsor, Nova Scotia Windsor is a community located in Hants County, Nova Scotia, Canada. It is a service centre for the western part of the county and is situated on Highway 101. The community has a history dating back to its use by the Mi'kmaq Nation for sev ...

, in 1868 by

Henry How Henry How (11 July 1828 – 28 September 1879) was a British-Canadian chemist, geologist and mineralogist. Career In 1847, How and August Wilhelm von Hofmann were co-workers at the Royal College in London. How was a professor of chemistry and ...

(1828–1879), a Canadian chemist, geologist, and mineralogist.H. How, "Contributions to the Mineralogy of Nova Scotia, Pt. III, Borates and Other Minerals in Anhydrite and Gypsum," Philosophical Magazine, January 1868Ramik, Robert A., "Lost and Found: one of Canada's earliest type mineral localities", The 32nd Rochester Mineralogical Symposium, Program and abstracts, Rochester, New York, April 14–17, 2005. How was alerted to the unknown mineral by miners in a gypsum quarry, who found it to be a nuisance. He called the new mineral silico-boro-calcite; it was given the name howlite by the American geologist

James Dwight Dana James Dwight Dana Royal Society of London, FRS FRSE (February 12, 1813 – April 14, 1895) was an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcano, volcanic activity, and the ...

shortly thereafter.

Geology

The most common form of howlite is irregular nodules, sometimes resembling cauliflower. Crystals of howlite are rare, having been found in only a couple localities worldwide. Crystals were first reported from Tick Canyon in the

Sierra Pelona Mountains The Sierra Pelona, also known as the Sierra Pelona Ridge or the Sierra Pelona Mountains, is a mountain ridge in the Transverse Ranges in Southern California. Located in northwest Los Angeles County, the ridge is bordered on the north by the San An ...

of California,Murdoch, J., "Crystallography and X-ray measurement of howlite from California", American Mineralogist, 42, 521-524, 1957. and later at

Iona, Nova Scotia Iona ( gd, Sanndraigh) is an unincorporated place in the Municipality of the County of Victoria, Cape Breton Island, Nova Scotia, Canada. It is named after Iona in Scotland. It is at the western end of the Barra Strait Bridge The Barra Stra ...

. Crystals reach a maximum size of about one centimeter. The nodules are white with fine grey or black veins in an erratic, often web-like pattern,

opaque Opacity or opaque may refer to: * Impediments to (especially, visible) light: ** Opacities, absorption coefficients ** Opacity (optics), property or degree of blocking the transmission of light * Metaphors derived from literal optics: ** In lingu ...

with a sub-vitreous luster. The crystals at Iona are colorless, white or brown and are often

translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...

transparent Transparency, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still, ...

. Its structure is

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

with a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 3.5 and lacks regular cleavage. Crystals are prismatic and flattened on . The crystals from Tick Canyon are elongated along the 010 axis, while those from Iona are elongated along the 001 axis.

Jewelry

Howlite is commonly used to make decorative objects such as small carvings or jewelry components. Because of its porous texture, howlite can be easily dyed to imitate other minerals, especially

turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of yea ...

because of the superficial similarity of the veining patterns. Howlite is also sold in its natural state, sometimes under the trade names of "white turquoise" or "white buffalo turquoise," or the derived name "white buffalo stone" and is used to produce jewelry similar to how turquoise is used. Varieties of the unrelated gemstone

which are white instead of the typical blue or green color have been mined in the US States of Arizona and Nevada, and are also marketed as "white buffalo turquoise". Most of the white varieties of turquoise are chalk-like with a

of 1, and are not as hard or durable as howlite, and subsequently require stabilization in order to be used in jewelry, which has resulted in howlite being more popular for use in jewelry than the artificially stabilized white forms of the mineral

Gallery

Image:Howlite-BYU.jpg, Howlite, as collected, southern California. Image:Howlite - tumble polished stone.jpg, A polished mass showing veining. Image:Howlite Crystal Form Nova Scotia.gif, Form of howlite crystals from Iona, Nova Scotia. Image:Howlite Crystal Form California.gif, Form of howlite crystals from Tick Canyon, California. Image:Howlite - turkenite.jpg, Howlite artificially colored in blue, and sold under the name turquenite. Image:Howlite-bolo.jpg, Howlite and Silver

Bolo tie A bolo tie (sometimes bola tie or shoestring necktie) is a type of necktie consisting of a piece of cord or braided leather with decorative metal tips (called aiguillettes) and secured with an ornamental clasp or slide. Popularity In the United ...

with small inclusions of tiny, brownish howlite crystals. This howlite specimen is from Tick Canyon Image:Elephant carved from howlite Length 10 cm arp.jpg, Elephant carved from howlite. Length 10 cm (4 in).

References

Bibliography