Aventurine is a form of quartzite, characterised by its translucency and the presence of platy mineral inclusions that give it a shimmering or glistening effect termed aventurescence .
Aventurine is a form of quartzite, characterised by its translucency and the presence of platy mineral inclusions that give it a shimmering or glistening effect termed aventurescence .
The most common color of aventurine is green, but it can also be orange, brown, yellow, blue, or grey. Chrome-bearing fuchsite (a variety of muscovite mica) is the classic inclusion and gives a silvery green or blue sheen. Oranges and browns are attributed to hematite or goethite. Because aventurine is a rock, its physical properties vary: its specific gravity may lie between 2.64–2.69 and its hardness is somewhat lower than single-crystal quartz at around 6.5.[ citation needed ]
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 at first glance.[ citation needed ]
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 One story runs that this kind of glass was originally made accidentally at Murano by a workman, who let some copper filings fall into the molten "metal", whence the product was called avventurino.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. [1] 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, dispersed within the glass in an unnaturally uniform manner. It is usually a golden brown, but may also be found in blue or green.[ citation needed ]
The majority of green and blue-green aventurine originates in India (particularly in the vicinity of Mysore and Chennai) where it is employed by prolific artisans. Creamy white, gray and orange material is found in Chile, Spain and Russia. Most material is carved into beads and figurines with only the finer examples fashioned into cabochons, later being set into jewellery.[ citation needed ]
Chalcedony ( kal-SED-ə-nee, or KAL-sə-doh-nee) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide).
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.
Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin lux, meaning "light", and generally implies radiance, gloss, or brilliance.
Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9 g/cm³. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.
Murano is a series of islands linked by bridges in the Venetian Lagoon, northern Italy. It lies about 1.5 km (1 mi) north of Venice and measures about 1.5 km (1 mi) across with a population of just over 5,000. It is famous for its glass making. It was once an independent comune, but is now a frazione of the comune of Venice.
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 and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.
In gemology, aventurescence is an optical reflectance effect seen in certain gems. The effect amounts to a metallic glitter, arising from minute, preferentially oriented mineral platelets within the material. These platelets are so numerous that they also influence the material's body colour. In aventurine quartz chrome-bearing fuchsite produces a green stone, and various iron oxides produce a red stone.
Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic carbonate with the chemical formula Cu3(CO3)2(OH)2, has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name kuanos (κυανός: "deep blue," root of English cyan) and the Latin name caeruleum. Copper (Cu2+) gives it its blue color.
Clinoclase is a hydrous copper arsenate mineral, Cu3AsO4(OH)3. Clinoclase is a rare secondary copper mineral and forms acicular crystals in the fractured weathered zone above copper sulfide deposits. It occurs in vitreous, translucent dark blue to dark greenish blue colored crystals and botryoidal masses. The crystal system is monoclinic 2/m. It has a hardness of 2.5–3 and a relative density of 4.3. Associated minerals include malachite, olivenite, quartz, limonite, adamite, azurite, and brochantite among others.
Dioptase is an intense emerald-green to bluish-green copper cyclosilicate mineral. It is transparent to translucent. Its luster is vitreous to sub-adamantine. Its formula is Cu6Si6O18·6H2O (also reported as CuSiO2(OH)2). It has a hardness of 5, the same as tooth enamel. Its specific gravity is 3.28–3.35, and it has two perfect and one very good cleavage directions. Additionally, dioptase is very fragile, and specimens must be handled with great care. It is a trigonal mineral, forming 6-sided crystals that are terminated by rhombohedra.
Chrysocolla ( KRIS-ə-KOL-ə) is a hydrous copper phyllosilicate mineral and mineraloid with the formula Cu
2 – xAl
x(H
2Si
2O
5)(OH)
4⋅nH
2O (x < 1) or (Cu, Al)
2H
2Si
2O
5(OH)
4⋅nH
2O).
Goldstone is a type of glittering glass made in a low-oxygen reducing atmosphere. The finished product can take a smooth polish and be carved into beads, figurines, or other artifacts suitable for semiprecious stone, and in fact goldstone is often mistaken for or misrepresented as a natural material.
Datolite is a calcium boron hydroxide nesosilicate, CaBSiO4(OH). It was first observed by Jens Esmark in 1806, and named by him from δατεῖσθαι, "to divide," and λίθος, "stone," in allusion to the granular structure of the massive mineral.
Sunstone is a microcline or oligoclase feldspar, which when viewed from certain directions exhibits a spangled appearance. It has been found in Southern Norway, Sweden, various United States localities and on some beaches along the midcoast of South Australia.
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is Cu4SO4(OH)6. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it was named by Armand Lévy for his fellow Frenchman, geologist and mineralogist A. J. M. Brochant de Villiers.
Bice, from the French bis, originally meaning dark-coloured, is a green or blue pigment. In French the terms vert bis and azur bis mean dark green and dark blue respectively. Bice pigments were generally prepared from basic copper carbonates, but sometimes ultramarine or other pigments were used.
Connellite is a rare mineral species, a hydrous copper chloro-sulfate, Cu19(OH)32(SO4)Cl4·3H2O, crystallizing in the hexagonal system. It occurs as tufts of very delicate acicular crystals of a fine blue color, and is associated with other copper minerals of secondary origin, such as cuprite and malachite. Its occurrence in Cornwall, England, was noted by Philip Rashleigh in 1802, and it was first examined chemically by Prof Arthur Connell FRSE in 1847, after whom it is named.
Optical mineralogy is the study of minerals and rocks by measuring their optical properties. Most commonly, rock and mineral samples are prepared as thin sections or grain mounts for study in the laboratory with a petrographic microscope. Optical mineralogy is used to identify the mineralogical composition of geological materials in order to help reveal their origin and evolution.
Murano beads are intricate glass beads influenced by Venetian glass artists. Since 1291, Murano glassmakers have refined technologies for producing beads and glasswork such as crystalline glass, enamelled glass (smalto), glass with threads of gold (aventurine), multicolored glass (millefiori), milk glass (lattimo) and imitation gemstones made of glass.
