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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. Heliotrope (mineral) - Wikipedia

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

    The mineral aggregate heliotrope (from Ancient Greek ἥλιος (hḗlios) 'sun' and τρέπειν (trépein) 'to turn'), also called Indian bloodstone or ematille, is a cryptocrystalline mixture of quartz that occurs mostly as jasper (opaque) or sometimes as chalcedony (translucent). The "classic" bloodstone is translucent to opaque green ...

  4. Iron(III) oxide - Wikipedia

    en.wikipedia.org/wiki/Iron(III)_oxide

    Iron (III) oxide in a vial. Iron (III) oxide or ferric oxide is the inorganic compound with the formula Fe 2 O 3. It is one of the three main oxides of iron, the other two being iron (II) oxide (FeO), which is rare; and iron (II,III) oxide (Fe 3 O 4), which also occurs naturally as the mineral magnetite.

  5. Concretion - Wikipedia

    en.wikipedia.org/wiki/Concretion

    Marlstone aggregate concretion, Sault Ste. Marie, Michigan, United States. A concretion is a hard, compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. [1] Concretions are often ovoid or spherical in shape, although irregular shapes also occur.

  6. Itabirite - Wikipedia

    en.wikipedia.org/wiki/Itabirite

    Itabirite, also called banded-quartz hematite or hematite schist, is a foliated, metamorphosed oxide-facies iron formation in which the original chert or jasper bands have been recrystallized into macroscopically distinguishable grains of quartz and the iron is present as thin layers of hematite, magnetite, or martite (pseudomorphs of hematite after magnetite).

  7. Mineral - Wikipedia

    en.wikipedia.org/wiki/Mineral

    Mineral. Crystals of serandite, natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada. In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. [1][2] The geological ...

  8. Aventurine - Wikipedia

    en.wikipedia.org/wiki/Aventurine

    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 ...

  9. Epitaxy - Wikipedia

    en.wikipedia.org/wiki/Epitaxy

    Epitaxy (prefix epi- means "on top of”) refers to a type of crystal growth or material deposition in which new crystalline layers are formed with one or more well-defined orientations with respect to the crystalline seed layer. The deposited crystalline film is called an epitaxial film or epitaxial layer. The relative orientation (s) of the ...