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Dogtooth spar is a speleothem that consists of large calcite crystals that form through mineral precipitation of water-borne calcite. Dogtooth spar crystals are found in caves, open spaces including veins and fractures, and geodes .
Dogtooth spar with fluorite from the Elmwood Mine in Tennessee. Spar is an old mining or mineralogy term used to refer to crystals that have readily discernible faces. A spar will easily break or cleave into rhomboidal, cubical, or laminated fragments with smooth shiny surfaces.
Metal-coated crystals are artificial products made by coating crystals, such as quartz, with metal to give them an iridescent metallic sheen. Crystals treated this way are used as gemstones and for other decorative purposes. Possible coatings include gold, indium, titanium, niobium and copper.
Boxwork in Wind Cave, South Dakota. In geology, boxwork is defined as a honeycomb-like structure that can form in some fractured or jointed sedimentary rocks. If the fractures in the host rock are mineralized, they can become more resistant to weathering than the surrounding rock, and subsequent erosion can produce boxwork structures.
Dogtooth, a 2009 film directed by Yorgos Lanthimos; Dog-tooth, an ornament found in medieval architecture; Dogtooth spar, a mineral deposit found in limestone caves; Dogtooth tuna, a species of pelagic marine fish; Dog's-tooth violet, a plant in the lily family; Dogtooth extension, a type of leading-edge extension on the wing of an aircraft
Quartz porphyry from the island of Alnö, Sweden. Phenocrysts of clear glassy rounded quartz and white orthoclase feldspar are set in a fine-grained matrix. Sample is just over 10 cm long. Quartz-porphyry, in layman's terms, is a type of volcanic rock containing large porphyritic crystals of quartz.
Quartzolite or silexite is an intrusive igneous rock, in which the mineral quartz is more than 90% of the rock's felsic mineral content, with feldspar at up to 10%. [ 1 ] : 135 [ 2 ] Typically, quartz forms more than 60% of the rock, [ 3 ] the rest being mostly feldspar although minor amounts of mica or amphibole may also be present. [ 2 ]
Diorama at Cahokia of flintknapper at work on hoes and bifaces. Chert is a siliceous (silica) stone, a variety of quartz similar to flint but more brittle. It naturally occurs as large, flat, elliptically shaped nodules in creek beds, and sometimes as hill-top residuum.