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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 oce ...
deposits.Howlite
at Mineral Galleries


History

Howlite was discovered near
Windsor, Nova Scotia Windsor is a community located in Hants County, Nova Scotia, Hants County, Nova Scotia, Canada. It is a service centre for the western part of the county and is situated on Nova Scotia Highway 101, Highway 101. The community has a history d ...
, in 1868 by Henry How (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 and originally known as the Liebre Mountains, is a mountain ridge in the Transverse Ranges in Southern California. Located in northwest Los Angeles County, t ...
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. 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 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 light scattering by particles, scattering of light. On a macroscopic scale ...
or transparent. Its structure is
monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...
with a
Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...
of 3.5 and lacks regular
cleavage Cleavage may refer to: Science * Cleavage (crystal), the way in which a crystal or mineral tends to split * Cleavage (embryo), the division of cells in an early embryo * Cleavage (geology), foliation of rock perpendicular to stress, a result of ...
. 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 hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue. The robi ...
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
turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue. The robi ...
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
Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...
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
turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue. The robi ...
.


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 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).


See also

*
List of minerals This is a list of minerals which have Wikipedia articles. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various ''species''. Within a mineral speci ...
*
List of minerals named after people This is a list of minerals named after people. The chemical composition of the mineral follows the name. A * Abelsonite: – American physicist Philip Hauge Abelson (1913–2004) * Abswurmbachite: – German mineralogist Irmgard Abs-Wurmbac ...
* Borate minerals


References


Bibliography

*Palache, P.; Berman H.; Frondel, C. (1960). "''Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)"'' John Wiley and Sons, Inc., New York, pp. 362–363. {{Jewellery Inoborates Monoclinic minerals Minerals in space group 14