Auerlite is a rare

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

variety, remarkably rich in thoria, named after

Carl Auer von Welsbach Carl Auer von Welsbach (1 September 1858 – 4 August 1929), who received the Austrian noble title of Freiherr Auer von Welsbach in 1901, was an Austrian scientist and inventor, who separated didymium into the elements neodymium and praseo ...

, the inventor of the Welsbach incandescent gas mantle. It is considered to be a phosphorus bearing variety of

thorite Thorite, (Th,U)SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon and hafnon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to ...

.Auerlite on Mindat.org
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Description

It was originally described as a hydrous silico-phosphate of

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...

, ThO₂(SiO₂,⅓P₂O₅)+2H₂O, i.e.

in which part of the

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

is replaced by

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...

. The crystals are tetragonal, lemon-yellow to brown-red in color, and sub-translucent to opaque. The mineral is very brittle; its

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

is 2.5 to 3, and its

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...

4.422 to 4.766, the darker crystals having the greatest density. Analysis gave the following results: —

Locations

This mineral has hitherto been found at only two places in

Henderson County, North Carolina Henderson County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 116,281. Its county seat is Hendersonville. Henderson County is part of the Asheville Metropolitan Statistical Area. Histor ...

, namely, at the Freeman mine, and on the Price land, to the southwest. At both places it occurs in disintegrated

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

ic rock, intimately associated with

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

crystals, on which it is often seen implanted.

Etymology

As this mineral was found while mining the zircons necessary to supply the demand caused by the invention of the system of incandescent gas lighting of Carl Auer von Welsbach, the authors of the original description proposed to name it Auerlite in his honour.

References

* * This work in turn cites: **{{Cite journal, journal=American Journal of Science, title=Auerlite, a new Thorium Mineral, volume=36, issue=216, pages=461–463, author=W. E. Hidden and J. B. Mackintosh, doi=10.2475/ajs.s3-36.216.461, year=1888, s2cid=130031763, url=https://zenodo.org/record/1450086 Tetragonal minerals Henderson County, North Carolina Thorium minerals