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Agate
Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Ancient Greece, in assorted jewelry and in the seal stones of Greek warriors, while bead necklaces with pierced and polished agate date back to the 3rd millennium BCE in the Indus Valley civilisation. Etymology The stone was given its name by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shore line of the Dirillo River or Achates ( grc, Ἀχάτης) in Sicily, sometime between the 4th and 3rd centuries BCE. Formation and properties Agate minerals have the tendency to form on or within pre-existing rocks, creating difficulties in accurately determining their time of formation. Their host rocks have been dated to have formed as early as the Archean Eon. Agates are most commonly found as nodules wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chalcedony
Chalcedony ( , or ) 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). Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black. The color of chalcedony sold commercially is often enhanced by dyeing or heating. The name ''chalcedony'' comes from the Latin ''chalcedonius'' (alternatively spelled ''calchedonius'') and is probably derived from the town of Chalcedon in Turkey. The name appears in Pliny the Elder's '' Naturalis Historia'' as a term for a translucent kind of jaspis. Another reference to a gem by the name of ''k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jewelry
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 western perspective, the term is restricted to durable ornaments, excluding flowers for example. For many centuries metal such as gold often combined with gemstones, has been the normal material for jewellery, but other materials such as glass, shells and other plant materials may be used. Jewellery is one of the oldest types of archaeological artefact – with 100,000-year-old beads made from '' Nassarius'' shells thought to be the oldest known jewellery.Study reveals 'oldest jewellery' , '' |
Turritella
''Turritella'' is a genus of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae.Vos, C.; Gofas, S. (2013). Turritella Lamarck, 1799. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138615 on 2013-06-02 They have tightly coiled shells, whose overall shape is basically that of an elongated cone. The name ''Turritella'' comes from the Latin word ''turritus'' meaning "turreted" or "towered" and the diminutive suffix ''-ella''. Species Valid Valid species within the genus ''Turritella'' are listed below. Fossil species are marked with a dagger "†". * ''Turritella acropora'' (Dall, 1889) * '' Turritella albolapis'' Finlay, 1924 * '' Turritella algida'' Melvill & Standen, 1912 * '' Turritella anactor'' Berry, 1957 * ''Turritella annulata'' Kiener, 1843 * † ''Turritella apicalis'' - Pleistocene of Florida * ''Turritella attenuata'' Reeve, 1849 * '' Turritella aurocincta'' Ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elimia Tenera
''Elimia tenera'' in chalcedony from Wyoming ">Wyoming.html" ;"title="chalcedony from Wyoming">chalcedony from Wyoming ''Elimia tenera'', formerly known as ''Goniobasis tenera'', is an extinct species of freshwater snail with an operculum (gastropod), operculum, in the aquatic gastropod mollusk family Pleuroceridae. This species flourished during the Eocene and is now known only from the fossil record. The genus name ''Elimia'' was restored to this species in 1975; formerly it was placed in '' Goniobasis''. Green River Formation deposits Fossilized ''Elimia tenera'' shells occur in a region which is now southern Wyoming, northern Colorado and northeastern Utah. The best preserved ''Elimia tenera'' are from Lake Gosiute which fossils occur in the Fort Laclede Bed of the Laney Member at outcrops in Sweetwater County, in southwestern Wyoming. 'Turritella agate' The fossils are hosted in chalcedony rich sedimentary rock. This rock was originally incorrectly called ''Turritell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seal Stone
Minoan seals are impression seals in the form of carved gemstones and similar pieces in metal, ivory and other materials produced in the Minoan civilization. They are an important part of Minoan art, and have been found in quantity at specific sites, for example in Knossos, Mallia and Phaistos. They were evidently used as a means of identifying documents and objects. Minoan seals are of a small size, 'pocket-size', in the manner of a personal amulet. Many of the images are a similar size to a human fingernail, with a high proportion that of the nail of a little finger. They might be thought of as equivalent to the pocket-sized, scaraboid seals of Ancient Egypt, which were sometimes imitated in Crete. However Minoan seals can be larger, with largest examples of many inches. Minoan seals are the most common surviving type of Minoan art after pottery, with several thousand known, from EM II onwards, in addition to over a thousand impressions, few of which match surviving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indus Valley Civilisation
The Indus Valley Civilisation (IVC), also known as the Indus Civilisation was a Bronze Age civilisation in the northwestern regions of South Asia, lasting from 3300 BCE to 1300 BCE, and in its mature form 2600 BCE to 1900 BCE. Together with ancient Egypt and Mesopotamia, it was one of three early civilisations of the Near East and South Asia, and of the three, the most widespread. Its sites spanned an area from much of Pakistan, to northeast Afghanistan, and northwestern India. The civilisation flourished both in the alluvial plain of the Indus River, which flows through the length of Pakistan, and along a system of perennial monsoon-fed rivers that once coursed in the vicinity of the Ghaggar-Hakra, a seasonal river in northwest India and eastern Pakistan. The term ''Harappan'' is sometimes applied to the Indus civilisation after its type site Harappa, the first to be excavated early in the 20th century in what was then the Punjab province ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dirillo
The Dirillo, or Acate, is a river in Sicily which springs from the Hyblaean Mountains and flows through the areas of Vizzini, Licodia Eubea, Mazzarrone, Chiaramonte Gulfi, Acate, Vittoria, Sicily, Vittoria, Gela. It enters the Strait of Sicily south-east of the town of Gela. As the largest river in the area it is sometimes known as the ''Fiume Grande''. The river was known in antiquity as the Achates ( grc, Ἀχάτης). It was noted by Silius Italicus for the remarkable clearness of its waters. Theophrastus in his treatise ''On Stones'' (ca. 315 B.C.) indicates that the name of the gemstone ''achates'' (agate) was based on the source of such stones from this river. Pliny the Elder makes the same connection in his ''Naturalis Historia'' [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classified as gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. Quartz is the mineral defining ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolomite (rock)
Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite rock from limestone was Belsazar Hacquet in 1778. Most dolomite was formed as a magnesium replacement of limestone or of lime mud before lithification. The geological process of conversion of calcite to dolomite is known as dolomitization and any intermediate product is known as dolomitic limestone. The "dolomite problem" refers to the vast worldwide depositions of dolomite in the past geologic record in contrast to the limited amounts of dolomite formed in modern times. Recent research has revealed sulfate-reducing bacteria living in anoxic conditions precipitate dolomite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archean
The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth during the Archean was mostly a water world: there was continental crust, but much of it was under an ocean deeper than today's ocean. Except for some trace minerals, today's oldest continental crust dates back to the Archean. Much of the geological detail of the Archean has been destroyed by subsequent activity. The earliest known life started in the Archean. Life was simple throughout the Archean, mostly represented by shallow-water microbial mats called stromatolites, and the atmosphere lacked free oxygen. Etymology and changes in classification The word ''Archean'' comes from the Greek word (), meaning 'beginning, origin'. It was first used in 1872, when it meant 'of the earliest geological age'. Before the Hadean Eon was recognized, the Arc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lace
Lace is a delicate fabric made of yarn or thread in an open weblike pattern, made by machine or by hand. Generally, lace is divided into two main categories, needlelace and bobbin lace, although there are other types of lace, such as knitted or crocheted lace. Other laces such as these are considered as a category of their specific craft. Knitted lace, therefore, is an example of knitting. This article considers both needle lace and bobbin lace. While some experts say both needle lace and bobbin lace began in Italy in the late 1500s, there are some questions regarding its origins. Originally linen, silk, gold, or silver threads were used. Now lace is often made with cotton thread, although linen and silk threads are still available. Manufactured lace may be made of synthetic fiber. A few modern artists make lace with a fine copper or silver wire instead of thread. Etymology The word lace is from Middle English, from Old French ''las'', noose, string, from Vulgar Latin *''l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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