Some igneous rock accessory minerals, such as apatite (a phosphate mineral), are

Question

Some igneous rock accessory minerals, such as apatite (a phosphate mineral), are by chemical weathering and are then [] as chemical sediments. Chemical sedimentary phosphate rock, along with now mostly worked out guano (accumulated dropping and remains of birds, bats, and seals), has been valued since the industrial revolution as a plant fertilizer. Also now, regretfully, phosphate is used as a component in terrorist made explosives. Chemical weathering releases the nutrients taken up by plants for their growth. Wood and accumulations of plant debris (peat, lignite, and coal) have long been used. Prospection for coal, however, began in carnest at the time of the industrial revolution and was the prime reason for the establishment of geological surveys elsewhere in the world than England after Roderick Impey Murchison published his book Silurian System in 1839. (He lost the sight of an eye hammering a rock a common injury a for geologist.) In his book, he made the case that Silurian strata predated terrestrial vegetation and so their presence in outcrop precluded the presence of [] there or below, so fruitless excavation could be avoided, and prospection for coal must be where there are younger strata. Hydrothermal minerals in bed rock and alluviums Water that is driven off from crystallizing magma penetrates the surrounding country rock. In this super- hot (as it is under high pressure) water, elements that do not combine to form accessory igneous rock minerals are carried off in solution to where they precipitate because the water [] or by reaction with the country rock. The result are hydrothermal deposits in quartz veins and pegmatites, and minerals disseminated in the country rock. Metals (alloys) used in the preindustrial world Bronze is made from amalgamations of copper and []; Pewter and Solder are made from amalgamations of tin and lead; and Brass is made from amalgamations of copper and []; As nature makes none of these discoveries of alchemy, people must find their components in separate places and bring them together. Metals prospected for in the preindutrial world were: native elements of copper (Cu), gold (Au) and platinum (PI) alloyed with it, and silver (Ag) leached cappings (gossans) of limonite (hydrated Fe-oxide) non silicate compounds of copper (Cu) (azurite, malachite, bornite), iron (Fe (magnetite, heamatite, limonite, gothite), lead (Pb)[], cerussite), mercury (Hg) (cinnabar), tin (Sn) (cassiterite), and zinc (Zn) ([]) (unavoidable but sometimes desired as amalgam additives) native arsenic (As), arsenic sulfides (orpiment, realgar), and arsenates (crythrite) Tin is an element in the resistate mineral cassiterite (an oxide mineral, SnO_2 that contains about 78.8 percent by weight tin). An historically important prospect for cassiterite was where granite intruded the country rock of Cornwall, southeastern tip of England (see below). Cassiterite occurs there as a mineral in tourmaline-rich quartz veins that extend out of the granite into the country rock. At the surface, gravity, stream gravels weathering releases cassiterite. As cassiterite has a high [] cassiterite is first powdered, a for minerals disclose. To the metal tin, the cassiterite is first powdered, mixed with powdered and coke (carbon), and then roasted in a furnace (SnO_2 + 2C => Sn + 2CO) to yield a melt of silver white metal and a driven off gas of carbon []. Impurities invariably present are sulphur that sublimates away, and arsenic and antimony that remains as an amalgamate.

Explanation / Answer

dissolved

precipitated

presence of coal

water cools

copper & tin

copper & zinc

Pb (Galena)

Zn (Sphalerite)

specific gravity

carbon monoxide

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