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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 ...
Mineral symbols (text abbreviations) are used to abbreviate mineral groups, subgroups, and species, just as lettered symbols are used for the chemical elements. The first set of commonly used mineral symbols was published in 1983 and covered the common rock-forming minerals using 192 two- or three-lettered symbols. [ 1 ]
Before buying any old gem, though, keep reading to uncover the 25 most popular gemstones—and their meanings. Agate “Agate is earthy, warm and rich,” Salzer says, noting that it exists in ...
A rare-earth mineral contains one or more rare-earth elements as major metal constituents. Rare-earth minerals are usually found in association with alkaline to peralkaline igneous magmas in pegmatites or with carbonatite intrusives. Perovskite mineral phases are common hosts to rare-earth elements within the alkaline complexes.
Minerals take on a botryoidal habit when they form in an environment containing many nuclei, specks of sand, dust, or other particulate matter to serve as sources of crystal nucleation. Acicular or fibrous crystals grow outward from these "seeds" at the same or very similar rate, resulting in radial crystal growth .
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.
Gemstones are basically categorized based on their crystal structure, specific gravity, refractive index, and other optical properties, such as pleochroism. The physical property of "hardness" is defined by the irregular Mohs scale of mineral hardness. Gemologists study these factors while valuing or appraising cut and polished gemstones.
For gem identification purposes, a pick-up response to a strong neodymium magnet separates garnet from all other natural transparent gemstones commonly used in the jewelry trade. Magnetic susceptibility measurements in conjunction with refractive index can be used to distinguish garnet species and varieties, and determine the composition of ...