Azure Spar

Azure spar, sometimes azur-spar, is a trivial and commercial, partly obsolete name for several of the most famous bright blue or blue-colored minerals, which also have similar names, most notably for lazurite and azurite,''Krivovichev V. G.'' Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0. ''(in Russian)'' and also for the less commonly used lazulite.''R. A. Lidin, L. L. Andreeva, V. A. Molochko''. Constants of inorganic substances: handbook. 3rd ed., reprinted, edited by R. A. Lidin. — Moscow: Drofa, 2008. — 685 p.

In addition, Robert Jameson in his fundamental works of 1804-1821 also included hauyne as a separate mineral species and the so-called ''“calaite”'', which in the 1820s meant only turquoise, among the azure feldspars.The Edinburgh Encyclopaedia, 1st American ed., Volume 13. — J. and E. Parker edition, 1832.

All of the listed minerals are known primarily as ornamental stones, and have historically been used as painting pigments and dyes for various purposes. More than others, lazurite or lapis lazuli has historically had a decorative use, classified by A. Fersman and M. Bauer as a ''first-order'' semi-precious ornamental stone. Haüyne is valued significantly higher than lapis lazuli, but it is rarely found in jewelry quality suitable for cutting. Azurite or copper azure is much less often used as an ornamental stone due to its fragility and chemical instability, but this mineral has been known since ancient times as a pigment for blue tempera paint, mainly in icon painting. Finally, lazulite is sometimes used not only as an ornamental stone, but also for jewelry cutting, although finds of high-quality raw materials are too rare for its mass use. As for turquoise, it has been one of the most popular ornamental and semi-precious stones since ancient times.

Main minerals

* Lazurite or ''lapis lazuli'' is an opaque mineral, sodium aluminosilicate sulfate with the ideal formula Na AlSiO₄)SO₄ having a color from blue to bluish- or greenish-gray, was previously widely known as azure spar.
* Haüyne or ''prismatic azure spar'' is a transparent or translucent mineral, similar to lazurite, in composition sodium and calcium aluminosilicate with the ideal formula (Na,Ca)_4-8Al₆Si₆(O,S)₂₄(SO₄,Cl)_1-2 having a blue or blue color, sometimes with a greenish tint,Depending on the impurities, white, grey or yellow-red hauyne is occasionally encountered, but these varieties are not considered to be “azure feldspars”. was also known among the azure spars.
* Azurite or ''copper azure'' is an opaque or slightly translucent mineral, copper bicarbonate in composition with the ideal formula Cu₃(СО₃)₂(ОН)₂, having a bright blue color, one of the most common secondary minerals containing copper, also known as azure spar.
* Lazulite or ''azure spar''Encyclopaedia Britannica, Volume fifth. — Edinburgh: printed for Archibald Constable and Company, 1824. is a transparent or translucent mineral, in composition a hydrous phosphate of iron, magnesium and aluminum with the ideal formula (Mg,Fe²⁺)Al₂(OH,PO₄)₂, having a beautiful sky-blue, light blue or bluish color, known as azure spar.
* Turquoise or ''kalaite'' is a widely known opaque mineral, which is a hydrated phosphate of aluminum and copper with the ideal formula CuAl₆ O₄sub>4(OH)₈·5H₂O, and is also included among the azure feldspars.

Azure Spars Gallery

Lazurite-236604.jpg,
Hauyne-169903.jpg,
Azurite-122803.jpg,
Lazulite-tmix07-168a.jpg,
Turchese, dal messico.JPG,

See also

* Feldspars
* Satin Spar
* Blue pigments
* Hauyne
* Ultramarine
* Azurite

References

{{Set index article
Set index articles on minerals
Pigments
Carbonate minerals
Sulfate minerals
Phosphate minerals
Silicate minerals
Sodium minerals
Aluminium minerals
Copper minerals
Iron minerals
Magnesium minerals
Mining terminology
Mineral groups