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Recognizing the habit can aid in mineral identification and description, as the crystal habit is an external representation of the internal ordered atomic arrangement. [1] Most natural crystals, however, do not display ideal habits and are commonly malformed. Hence, it is also important to describe the quality of the shape of a mineral specimen:
The chiastolite crystals have been pseudomorphically altered by a mixture of muscovite, paragonite and margarite. The calcium-rich margarite tends to form along the graphite-rich crosses or bands within the chiastolite. Mineralogically the occurrence is important because all three white mica phases are present in an equilibrium assemblage. [4]
Amethyst crystals – a purple quartz Apophyllite crystals sitting right beside a cluster of peachy bowtie stilbite Aquamarine variety of beryl with tourmaline on orthoclase Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals Austinite from the Ojuela Mine, Mapimí, Durango, Mexico Ametrine ...
Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na 2 (Fe 2+ 3 Fe 3+ 2)Si 8 O 22 (OH) 2.It forms a solid solution series with magnesioriebeckite.
Well-developed crystals are found at many localities: Knappenwand, near the Großvenediger in the Untersulzbachthal in Salzburg, as magnificent, dark green crystals of long prismatic habit in cavities in epidote schist, with asbestos, adularia, calcite, and apatite; the Ala valley and Traversella in Piedmont; Arendal in Norway; Le Bourg-d ...
Grape Agate is a market name for purple aggregates of tiny quartz crystals with botryoidal (spherical) habit. [1] Mineralogically speaking, grape agate is not an agate [2] and is actually botryoidal purple chalcedony. [3] It occurs in Indonesia [2] and has also been found west of the Green river in Utah. [4]: 75
The scuppernong is a large variety of muscadine (Vitis rotundifolia), [1] a species of grape native to the southern United States. It is usually a greenish or bronze color and is similar in appearance and texture to a white grape, but rounder and larger.
Kyanite also shows a parting on {001} at an angle of about 85 degrees to the long axis of the crystal. [7] Cleavage surfaces typically display a pearly luster. The crystals are slightly flexible. [6] Kyanite's elongated, columnar crystals are usually a good first indication of the mineral, as well as its color (when the specimen is blue).