In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
Marble is a metamorphic rock consisting of carbonate minerals that recrystallize under the influence of heat, pressure, and aqueous solutions (most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2) and has a crystalline texture of varying thickness. Marble is typically not foliated (layered), although there are exceptions.
Sandstone is a clastic sedimentary rock composed mainly of sand-sized silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.
Serpentine subgroup are greenish, brownish, or spotted minerals commonly found in serpentinite. They are used as a source of magnesium and asbestos, and as decorative stone. The name comes from the greenish colour and smooth or scaly appearance from the Latin serpentinus, meaning "serpent rock".
Magnesite is a mineral with the chemical formula MgCO
3. Iron, manganese, cobalt, and nickel may occur as admixtures, but only in small amounts.
Peridotite ( PERR-ih-doh-tyte, pə-RID-ə-) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole.
Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. These properties are caused by fine grained non-aligned crystals with platy or prismatic habits, characteristic of metamorphism at high temperature but without accompanying deformation. The term is derived from the German word Hornfels, meaning "hornstone", because of its exceptional toughness and texture both reminiscent of animal horns. These rocks were referred to by miners in northern England as whetstones.
Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called serpentine or serpentine rock, particularly in older geological texts and in wider cultural settings.
Serpentinization is a hydration and metamorphic transformation of ferromagnesian minerals, such as olivine and pyroxene, in mafic and ultramafic rock to produce serpentinite. Minerals formed by serpentinization include the serpentine group minerals, brucite, talc, Ni-Fe alloys, and magnetite. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.
Komatiite is a type of ultramafic mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% magnesium oxide (MgO). It is classified as a 'picritic rock'. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its type locality along the Komati River in South Africa, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene.
Talc carbonates are a suite of rock and mineral compositions found in metamorphosed ultramafic rocks.
A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures. The assemblage is typical of what is formed in conditions corresponding to an area on the two dimensional graph of temperature vs. pressure. Rocks which contain certain minerals can therefore be linked to certain tectonic settings, times and places in the geological history of the area. The boundaries between facies are wide because they are gradational and approximate. The area on the graph corresponding to rock formation at the lowest values of temperature and pressure is the range of formation of sedimentary rocks, as opposed to metamorphic rocks, in a process called diagenesis.
St. Patrick's Catholic Church is a Catholic church in San Francisco, California, founded in 1851. It is located at 756 Mission Street, between 3rd and 4th streets, across the street from Yerba Buena Gardens in the heart of the South of Market district.
Sala Silver Mine is a mine in Sala Municipality, in Västmanland County in Sweden. The mine was in continuous production from the 15th century until 1908. Additional mining occurred in 1950–1951 and also in 1945–1962 in the neighbouring Bronäs Mine.
Verd antique, also called verde antique, marmor thessalicum, or Ophite, is a serpentinite breccia popular since ancient times as a decorative facing stone. It is a dark, dull green, white-mottled serpentine, mixed with calcite, dolomite, or magnesite, which takes a high polish. The term verd antique has been documented in English texts as early as 1745.
Bernard Elgey Leake is an English geologist. He is Emeritus Professor of Geology at the University of Glasgow, was Leverhulme Emeritus Fellow at Cardiff University 2000-2002 and has been an Honorary Research Fellow at Cardiff University since 1997.
The Merlis Serpentinites are an aligned group of small serpentinite outcrops in the northwestern French Massif Central. Their parent rocks were peridotites from the upper mantle.
A subduction zone is a region of the Earth's crust where one tectonic plate moves under another tectonic plate; oceanic crust gets recycled back into the mantle and continental crust gets created by the formation of arc magmas. Arc magmas account for more than 20% of terrestrially produced magmas and are produced by the dehydration of minerals within the subducting slab as it descends into the mantle and are accreted onto the base of the overriding continental plate. Subduction zones host a unique variety of rock types created by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. The metamorphic conditions the slab passes through in this process creates and destroys water bearing (hydrous) mineral phases, releasing water into the mantle. This water lowers the melting point of mantle rock, initiating melting. Understanding the timing and conditions in which these dehydration reactions occur, is key to interpreting mantle melting, volcanic arc magmatism, and the formation of continental crust.
