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Crystal habit. 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 due to limited space in the crystallizing medium (commonly in rocks). [1][2]
Cubic, faces may be striated, but also frequently octahedral and pyritohedral. Often inter-grown, massive, radiated, granular, globular, and stalactitic. The mineral pyrite (/ ˈpaɪraɪt / PY-ryte), [6] or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S 2 (iron (II) disulfide).
Crystal twinning. Quartz – Japan twin. Diagram of twinned crystals of albite. On the more perfect cleavage, which is parallel to the basal plane (P), is a system of fine striations, parallel to the second cleavage (M). Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the ...
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. The opposite is anhedral (also known as xenomorphic or allotriomorphic), which describes rock with a microstructure ...
Amethyst is a purple variety of quartz (SiO. 2) and owes its violet color to irradiation, impurities of iron (Fe3+. ) and in some cases other transition metals, and the presence of other trace elements, which result in complex crystal lattice substitutions. [2][3][4] The irradiation causes the iron Fe3+.
A framboid is a micromorphological feature common to certain sedimentary minerals, particularly pyrite (FeS 2). The first known use of the term is ascribed to Rust in 1935 and is derived from the French 'framboise', meaning 'raspberry', reflecting the appearance of the structure under magnification. Framboidal structure comprises roughly ...
Galena, also called lead glance, is the natural mineral form of lead (II) sulfide (PbS). It is the most important ore of lead and an important source of silver. [5] Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms.
The pyrite group of minerals is a set of cubic crystal system minerals with diploidal structure. Each metallic element is bonded to six "dumbbell" pairs of non-metallic elements and each "dumbbell" pair is bonded to six metal atoms. [1][2] The group is named for its most common member, pyrite (fool's gold), which is sometimes explicitly ...