Auerlite is a rare North Carolina

North Carolina

North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 mineral

Mineral

A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

, remarkably rich in thoria, named after Carl Auer von Welsbach

Carl Auer von Welsbach

Carl Auer Freiherr von Welsbach was an Austrian scientist and inventor who had a talent for not only discovering advances, but turning them into commercially successful products...

, the inventor of the Welsbach incandescent gas mantel.

Description

It was originally described as a hydrous silico-phosphate of thorium

Thorium

Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....

, ThO₂(SiO₂,⅓P₂O₅)+2H₂O, i.e. thorite

Thorite

Thorite, 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 reflect its thorium content...

 in which part of the silica is replaced by phosphoric acid

Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...

. The crystals are tetragonal, lemon-yellow to brown-red in colour, and sub-translucent to opaque. The mineral is very brittle; its hardness is 2.5 to 3, and its specific gravity

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 4.422 to 4.766, the darker crystals having the greatest density.

Analysis gave the following results: —

H2O	CO2	SiO2	P2O5	ThO2	Fe2O3	CaO	MgO	Al2O3	Total
10.21	1.00	7.64	7.46	70.13	1.38	0.49	0.29	1.10	99.70

Locations

This mineral has hitherto been found at only two places in Henderson County, North Carolina

Henderson County, North Carolina

Henderson County is a county located in the U.S. state of North Carolina. It is part of the Asheville, North Carolina, Metropolitan Statistical Area. As of 2008, the population was 102,367. Its county seat is Hendersonville.- History :...

, namely, at the Freeman mine, and on the Price land, 3 miles (4.8 km) to the southwest. At both places it occurs in disintegrated granitic

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 or gneiss

Gneiss

Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...

ic rock, intimately associated with zircon

Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...

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.