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  2. Hematite - Wikipedia

    en.wikipedia.org/wiki/Hematite

    Hematite (/ ˈ h iː m ə ˌ t aɪ t, ˈ h ɛ m ə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe 2 O 3 and is widely found in rocks and soils. [6] Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe 2 O 3. It has the same crystal structure as corundum ...

  3. List of gemstones by species - Wikipedia

    en.wikipedia.org/wiki/List_of_gemstones_by_species

    Eilat stone; Epidosite; Glimmerite; Goldstone (glittering glass) Hawk's eye; Helenite (artificial glass made from volcanic ash) Iddingsite; Kimberlite; Lamproite; Lapis lazuli; Libyan desert glass; Llanite; Maw sit sit; Moldavite; Obsidian; Apache tears; Pallasite; Peridotite (also known as olivinite) Siilinjärvi carbonatite; Soapstone (also ...

  4. List of U.S. state minerals, rocks, stones and gemstones

    en.wikipedia.org/wiki/List_of_U.S._state...

    Leaders of states in the U.S. which have significant mineral deposits often create a state mineral, rock, stone or gemstone to promote interest in their natural resources, history, tourism, etc. Not every state has an official state mineral, rock, stone and/or gemstone, however.

  5. Heliotrope (mineral) - Wikipedia

    en.wikipedia.org/wiki/Heliotrope_(mineral)

    The Gnostics wore the stone as an amulet for longevity, for wealth and courage, to strengthen the stomach, and to dispel melancholy. [6] In the Middle Ages it was considered useful for animal husbandry. [6] The ancient Greeks and Romans wore the stone to bring renown and favor, to bring endurance, and as a charm against the bite of venomous ...

  6. Sunstone - Wikipedia

    en.wikipedia.org/wiki/Sunstone

    Oregon Sunstone is unique in that crystals can be quite large. The copper leads to variant color within some stones, where turning one stone will result in manifold hues: the more copper within the stone, the darker the complexion. [9] On August 4, 1987, the Oregon State Legislature designated Oregon Sunstone as its state gemstone by joint ...

  7. List of individual gemstones - Wikipedia

    en.wikipedia.org/wiki/List_of_individual_gemstones

    Emerald of Saint Louis, [5] 51.60 carats cut; discovered in Austria, probably Habachtal, resides in the National Museum of Natural History, Paris Gachalá Emerald [ 6 ] Mogul Mughal Emerald , 217.80 carats cut; mined in Colombia and cut in the Mughal empire in Hijri year 1107 (1695–1696), resides in the Museum of Islamic Art, Doha , Qatar [ 7 ...

  8. Cupstone - Wikipedia

    en.wikipedia.org/wiki/Cupstone

    Similar objects can be found on all continents except Antarctica. They are associated with Celtic Europe, prehistoric Australia, Borneo and the Middle East.Some of the earliest cupules can be found at the Bhimbetka cave site in India, dating to 290,000-700,000 BCE, but in Europe they do not pre-date the most recent cold phase (the Würm or Weichselian glaciation).

  9. Magnetite - Wikipedia

    en.wikipedia.org/wiki/Magnetite

    Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the mineral pair forms a buffer that can control how oxidizing its environment is (the oxygen fugacity). This buffer is known as the hematite-magnetite or HM buffer.