Diabase or Dolerite Diabase or dolerite is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. See more. Porphyritic mafic volcanic rock with large plagioclase phenocrysts. Soil profiles as indicators of mineral weathering rates and organic interactions for a Pennsylvania diabase E.M. Hausrath a,⁎, A.K. Basalt has a strict chemical definition. The Sierra Ancha olivine diabase has a high-alumina olivine basalt composition There are a variety of Diabase Uses and the Diabase Reserves are found in many countries around the world. The composition of the sill is that of diabase, although its mineral assemblage is not uniform throughout the thickness of the body. Brantley c a University of Nevada, Las b Gabbro is greenish and dark. Ophitic texture (randomly oriented plagioclase laths enclosed by pyroxene grains) is a characteristic feature of diabase. Diabase is a fine-grained igneous rock which is composed mostly of pyroxene and feldspar Diorite is a grey to dark-grey intermediate intrusive igneous rock composed principally of plagioclase feldspar,biotite, hornblende, and pyroxene 1.2 History 1.2.1 Origin Accessory and alteration minerals include hornblende, biotite, apatite, pyrrhotite, chalcopyrite, serpentine, chlorite, and calcite. Diabase is a popular ornamental stone. In British and Australian usage: A medium grained mafic intrusive rock whose main components are calcic plagioclase and clinopyroxene and which is characterized by ophitic to subophitic texture; usually found in sills and dykes. Mushroom Rock in Death Valley is carved from dolerite. Crushed stone is often made of it and it seems to be a popular choice to use in sauna heaters. The rock is 8 cm in length. Nevertheless, the mineral composition of the unaltered basalt flows in the bottom third of the sequence is similar to that of the diabase sills, which suggested that those lavas and the diabase sills were co-magmatic and probably coeval. The width of the view is 25 cm. Chemically and mineralogically, diabase closely resembles the volcanic rock basalt, but it is somewhat coarser and contains glass. Dolerite definition, a coarse-grained variety of basalt. Reproduced from Christensen NI (1996 $" Brongniart named so rocks that were composed of feldspar and hornblende. Diabase is actually a variety of gabbro which consists mainly of labradorite feldspar, augite, magnetite, and olivine. Mineral Composition of Diabase Diabase typically has a mineral composition that is dominated by the plagioclase feldspar known as labradorite (approximately 40% to 70% of the rock). When identifying the mineral assemblage of igneous rocks, color is often a good place to start. According to him, only rocks of pre-Tertiary (pre-Cenozoic) age were named diabase. Brown spots are left by sea animals that were attached to the rock. Unknown locality. unaltered dolostone, the silicified dolostone, and the diabase in order to establish the mineral. Diabase (dolerite) is a dark-colored igneous rock. However, it somehow managed to survive, mostly thanks to German scholars who continued to use it but now to refer to the rocks which were composed of pyroxene and plagioclase. Diabase is a common rock type. The width of the view is 14 cm. Amphibolization in diabase and sericitization in slate are characteristically predominant in this mining area. Most of the remainder is made up of pyroxene minerals (usually augite ). The basaltic dike is fine-grained because it is younger and was chilled (it lost heat rapidly to the diabase dike on the right). Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine grained to aphanitic chilled margins which may contain tachylite (dark mafic glass). The 2.2 Ga Nipissing Diabase is a voluminous suite of mafic intrusive rocks in the Southern Province, Ontario, extending over an area of 250 km, covering ~25% of … studied. The rocks in the earth’s crust continuously undergo changes in their composition which leads to formation of other rocks. The good physical and chemical properties of the In the United States, an intrusive rock whose main components are labradorite and pyroxene and that is characterized by ophitic texture. This sample is taken from a drillcore. The age criterion is not in use anymore, but both “dolerite” and “diabase” continue to be used. Magnetite, and calcite ophitic texture ( randomly oriented plagioclase laths enclosed by grains! 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