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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]
Pyrophyllite, a mineral very similar to talc, is sometimes called soapstone in the generic sense, since its physical characteristics and industrial uses are similar, [3] and because it is also commonly used as a carving material. However, this mineral typically does not have such a soapy feel as soapstone.
The original rock, known as the protolith, transforms into other mineral types or other forms of the same minerals, by recrystallization. [5] The temperatures and pressures required for this process are always higher than those found at the Earth's surface: temperatures greater than 150 to 200 °C and pressures greater than 1500 bars. [ 18 ]
Mineralogy applies principles of chemistry, geology, physics and materials science to the study of minerals. 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 ...
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 +
The oldest peneplain identifiable in a shield is called a "primary peneplain"; [5] in the case of the Fennoscandian Shield, this is the Sub-Cambrian peneplain. [ 6 ] The landforms and shallow deposits of northern shields that have been subject to Quaternary glaciation and periglaciation are distinct from those found closer to the equator. [ 5 ]
Physical characteristics include colour, texture, grain size, and composition. [ 1 ] [ 2 ] [ 3 ] Lithology may refer to either a detailed description of these characteristics, or a summary of the gross physical character of a rock.
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.