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A speleothem (/ ˈ s p iː l i ə θ ɛ m /; from Ancient Greek σπήλαιον (spḗlaion) 'cave' and θέμα (théma) 'deposit') is a geological formation made by mineral deposits that accumulate over time in natural caves. [1] Speleothems most commonly form in calcareous caves due to carbonate dissolution reactions. They can take a ...
For example, the skeletal density of kerogen increases from approximately 1.1 g/ml at low thermal maturity to 1.7 g/ml at high thermal maturity. [ 30 ] [ 31 ] [ 32 ] This evolution is consistent with the change in carbon speciation from predominantly aliphatic (similar to wax, density < 1 g/ml) to predominantly aromatic (similar to graphite ...
Orthoclase feldspar (KAlSi 3 O 8) is a mineral commonly found in granite, a plutonic igneous rock. When exposed to weathering, it reacts to form kaolinite (Al 2 Si 2 O 5 (OH) 4, a sedimentary mineral, and silicic acid): 2 KAlSi 3 O 8 + 5 H 2 O + 2 H + → Al 2 Si 2 O 5 (OH) 4 + 4 H 2 SiO 3 + 2 K +
It is thought that they averaged heights of 1.2–1.5 metres (3.9–4.9 ft) and weighed between 30 and 55 kilograms (66 and 121 lb). The brain size may have been 350 cc to 600 cc. The postcanines (the teeth behind the canines) were relatively large, and had more enamel compared to contemporary apes and humans, whereas the incisors and canines ...
Pyrolusite is a mineral consisting essentially of manganese dioxide (Mn O 2) and is important as an ore of manganese. [7] It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform crusts.
Mineralogy [n 1] is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical ...
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The formula of the admixture of the three most common endmembers is written as Ca 10 (PO 4) 6 (OH,F,Cl) 2, and the crystal unit cell formulae of the individual minerals are written as Ca 10 (PO 4) 6 (OH) 2, Ca 10 (PO 4) 6 F 2 and Ca 10 (PO 4) 6 Cl 2. The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, [4 ...