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2. Crystal habit - Wikipedia

   en.wikipedia.org/wiki/Crystal_habit

   Smoky quartz with spessartine on top of feldspar matrix, featuring different crystal habits (shapes) In mineralogy, crystal habit is the characteristic external shape of an individual crystal or aggregate of crystals. The habit of a crystal is dependent on its crystallographic form and growth conditions, which generally creates irregularities ...

3. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   A synthetic quartz crystal grown by the hydrothermal method, about 19 centimetres (7.5 in) long and weighing about 127 grams (4.5 oz) Not all varieties of quartz are naturally occurring. Some clear quartz crystals can be treated using heat or gamma-irradiation to induce color where it would not otherwise have occurred naturally. Susceptibility ...

4. Druse (geology) - Wikipedia

   en.wikipedia.org/wiki/Druse_(geology)

   Druse quartz crystals Druse of uvarovite from the Urals; ... druse is a crystal habit represented by the coating of fine crystals on a rock fracture surface, [1] ...

5. Acicular (crystal habit) - Wikipedia

   en.wikipedia.org/wiki/Acicular_(crystal_habit)

   Acicular, in mineralogy, refers to a crystal habit composed of slender, needle-like crystals. Crystals with this habit tend to be fragile. Complete, undamaged acicular specimens are uncommon. Needle-shaped acicular millerite crystals on white quartz. The term "acicular" derives from the Late Latin "acicula" meaning "little needle". [1] Strictly ...

6. Smoky quartz - Wikipedia

   en.wikipedia.org/wiki/Smoky_quartz

   Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. [6] The color of smoky quartz is produced when natural radiation, emitted from the surrounding rock, activates color centers around aluminum impurities within the ...

7. Molybdenite - Wikipedia

   en.wikipedia.org/wiki/Molybdenite

   Crystal habit: Thin, platy hexagonal crystals terminated by pinacoidal faces, also as tapering six-sided pyramids that can be truncated by the pinacoids. Also massive, lamellar and in small grains in sulfide ore bodies: Cleavage: Perfect on [0001] Tenacity: Lamellae flexible, not elastic: Mohs scale hardness: 1–1.5: Luster: Metallic: Streak ...

8. Prism (geology) - Wikipedia

   en.wikipedia.org/wiki/Prism_(geology)

   Hexagonal aquamarine prism with stubby quartz prisms. In mineralogy, prismatic is also type of mineral habit (appearance of a crystal). Prismatic minerals have crystals that show a uniform cross-section. Prismatic crystals typically have 3, 4, 6, 8 or 12 faces which are parallel to a crystallographic axis. [2]

9. Euhedral and anhedral - Wikipedia

   en.wikipedia.org/wiki/Euhedral_and_anhedral

   Euhedral pyrite crystals A subhedral sample showing sharp to anhedral pyrargyrite crystals. Euhedral and anhedral are terms used to describe opposite properties in the formation of crystals . Euhedral (also known as idiomorphic or automorphic ) crystals are those that are well-formed, with sharp, easily recognised faces .