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H 2 O + CO 2 → H 2 CO 3. As the acidic water travels through the calcium carbonate bedrock from the surface to the cave ceiling, it dissolves the bedrock via the reaction: CaCO 3 + H 2 CO 3 → Ca 2+ + 2 HCO 3 −. When the solution reaches a cave, the lower pCO 2 in the cave drives the precipitation of CaCO 3 via the reaction: Ca 2+ + 2 HCO ...
Corundum group minerals have a 2:3 ratio, and includes minerals such as corundum (Al 2 O 3), and hematite (Fe 2 O 3). Rutile group minerals have a ratio of 1:2; the eponymous species, rutile (TiO 2) is the chief ore of titanium; other examples include cassiterite (SnO 2; ore of tin), and pyrolusite (MnO 2; ore of manganese).
It commonly contains minor quantities of other oxides such as CaO or Al 2 O 3. 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 ...
Anorthosite (/ ə ˈ n ɔːr θ ə s aɪ t /) is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%).
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.
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 ]
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 ]
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 ...