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The source of obsidian for cultures inhabiting the territory of and around Greece was the island of Milos; the Starčevo–Körös–Criș culture obtained obsidian from sources in Hungary and Slovakia, while the Cardium-Impresso cultural complex acquired obsidian from the island outcrops of the central Mediterranean.
This is a list of minerals which have Wikipedia articles. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species .
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Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as ...
Opals too thin to produce a "natural" opal may be combined with other materials to form "composite" gems. An opal doublet consists of a relatively thin layer of precious opal, backed by a layer of dark-colored material, most commonly ironstone, dark or black common opal (potch), onyx, or obsidian. The darker backing emphasizes the play of color ...
Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently.
Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
The cavities are filled with many secondary minerals, such as calcite, chlorite, quartz, epidote, or chalcedony; in microscopic sections, though, the nature of the original lava can nearly always be made out from the shapes and properties of the little crystals which occur in the decomposed glassy base.