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  2. Proustite - Wikipedia

    en.wikipedia.org/wiki/Proustite

    It is associated with other silver minerals and sulfides such as native silver, native arsenic, xanthoconite, stephanite, acanthite, tetrahedrite and chlorargyrite. [ 2 ] Magnificent groups of large crystals have been found at Chañarcillo in Chile ; other localities which have yielded fine specimens are Freiberg and Marienberg in Saxony ...

  3. Obsidian use in Mesoamerica - Wikipedia

    en.wikipedia.org/wiki/Obsidian_use_in_Mesoamerica

    Obsidian projectile point.. Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica.Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy.

  4. Obsidian - Wikipedia

    en.wikipedia.org/wiki/Obsidian

    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.

  5. Helenite - Wikipedia

    en.wikipedia.org/wiki/Helenite

    Helenite, also known as Mount St. Helens obsidian, emerald obsidianite, and ruby obsidianite, is a glass made from the fused volcanic rock dust from Mount St. Helens and marketed as a gemstone. [ 1 ] [ 2 ] Helenite was first created accidentally after the eruption of Mount St. Helens in 1980 .

  6. Conservation and restoration of silver objects - Wikipedia

    en.wikipedia.org/wiki/Conservation_and...

    Whether silver plating or pure silver, the composite of the metal will tarnish when exposed to air and sulfur. Tarnish is a chemical reaction on the surface of metal (copper, brass, silver, etc.) and causes a layer of corrosion. In the case of silver tarnish, the silver combines with sulfur and forms silver sulfide (Ag 2 S), which is

  7. Crystal healing - Wikipedia

    en.wikipedia.org/wiki/Crystal_healing

    Crystal healing is a pseudoscientific alternative-medicine practice that uses semiprecious stones and crystals such as quartz, agate, amethyst or opal. Despite the common use of the term "crystal", many popular stones used in crystal healing, such as obsidian, are not technically crystals. Adherents of the practice claim that these have healing ...

  8. Obsidian hydration dating - Wikipedia

    en.wikipedia.org/wiki/Obsidian_hydration_dating

    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 ...

  9. Apache tears - Wikipedia

    en.wikipedia.org/wiki/Apache_tears

    Apache tears are rounded pebbles of obsidian or "obsidianites" composed of black or dark-colored natural volcanic glass, usually of rhyolitic composition and bearing conchoidal fracture. Also known by the lithologic term marekanite , this variety of obsidian occurs as subrounded to subangular bodies up to about 2 in (51 mm) in diameter, often ...