Aventurine is a form of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

, characterised by its translucency and the presence of platy

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. ( ...

inclusion Inclusion or Include may refer to: Sociology * Social inclusion, aims to create an environment that supports equal opportunity for individuals and groups that form a society. ** Inclusion (disability rights), promotion of people with disabilitie ...

s that give it a shimmering or glistening effect termed '' aventurescence''.

Background

The most common color of aventurine is green, but it can also be orange, brown, yellow, blue, or grey. Chrome-bearing

fuchsite Fuchsite, also known as chrome mica, is a chromium (Cr) rich variety of the mineral muscovite, belonging to the mica group of phyllosilicate minerals, with the chemical formula . Trivalent chromium replaces one of the aluminium (Al) atoms in the ...

(a variety of muscovite

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

) is the classic inclusion and gives a silvery green or blue sheen. Oranges and browns are attributed to

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

or goethite. Because aventurine is a

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...

, its physical properties vary: 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 (molecule), wa ...

may lie between 2.64-2.69 and 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 somewhat lower than single-crystal quartz at around 6.5. AventurinGeschliffen

Aventurine feldspar or sunstone can be confused with orange and red aventurine quartzite, although the former is generally of a higher transparency. Aventurine is often banded and an overabundance of fuchsite may render it opaque, in which case it may be mistaken for

malachite Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures ...

at first glance. The name ''aventurine'' derives from the Italian "a ventura" meaning "by chance." This is an allusion to the lucky discovery of aventurine glass or goldstone at some point in the 18th century. One story runs that this kind of glass was originally made accidentally at Murano by a workman, who let some copper filings fall into the molten “metal,” whence the product was called ''avventurino''. From the Murano glass the name passed to the mineral, which displayed a rather similar appearance. Although it was known first, goldstone is now a common imitation of aventurine and sunstone. Goldstone is distinguished visually from the latter two minerals by its coarse flecks of

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

, dispersed within the glass in an unnaturally uniform manner. It is usually a golden brown, but may also be found in blue or green. The majority of green and blue-green aventurine originates in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

(particularly in the vicinity of

Mysore Mysore (), officially Mysuru (), is a city in the southern part of the state of Karnataka, India. Mysore city is geographically located between 12° 18′ 26″ north latitude and 76° 38′ 59″ east longitude. It is located at an altitude of ...

and

Chennai Chennai (, ), formerly known as Madras ( the official name until 1996), is the capital city of Tamil Nadu, the southernmost Indian state. The largest city of the state in area and population, Chennai is located on the Coromandel Coast of th ...

) where it is employed by prolific artisans. Creamy white, gray and orange material is found in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

and

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. Most material is carved into beads and figurines with only the finer examples fashioned into cabochons, later being set into

jewellery Jewellery ( UK) or jewelry (U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a wester ...

References

External links

Aventurine
at Mindat.org {{Jewellery Chalcedony Quartz gemstones

Background

See also

References

External links