Search results
Results from the WOW.Com Content Network
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 ...
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, although ...
Soapstone is often used as an insulator for housing and electrical components, due to its durability and electrical characteristics and because it can be pressed into complex shapes before firing. Soapstone undergoes transformations when heated to temperatures of 1,000–1,200 °C (1,830–2,190 °F) into enstatite and cristobalite ; on the ...
The kaolinite-serpentine group consists of T-O stacks (the 1:1 clay minerals); their hardness ranges from 2 to 4, as the sheets are held by hydrogen bonds. The 2:1 clay minerals (pyrophyllite-talc) consist of T-O-T stacks, but they are softer (hardness from 1 to 2), as they are instead held together by van der Waals forces.
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 ...
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 ]
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. Examples of lithologies in the second sense include sandstone, slate, basalt, or limestone. [4]
Within 1.5–2 km (0.93–1.24 mi) of the surface, the highly pressured magma explodes upwards and expands to form a conical to cylindrical diatreme, which erupts to the surface. The surface expression is rarely preserved but is usually similar to a maar volcano. Kimberlite dikes and sills can be thin (1–4 meters), while pipes range in ...