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Aquamarine variety of beryl with tourmaline on orthoclase. Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico. Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals. Austinite from the Ojuela Mine, Mapimí, Durango, Mexico. Ametrine containing amethyst and citrine, from Bolivia.
An American-style crossword grid layout. A crossword(or crossword puzzle) is a word gameconsisting of a grid of black and white squares, into which solvers enter words or phrases ("entries") crossing each other horizontally ("across") and vertically ("down") according to a set of clues. Each white square is typically filled with one letter ...
Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235 U) has been increased through the process of isotope separation.Naturally occurring uranium is composed of three major isotopes: uranium-238 (238 U with 99.2732–99.2752% natural abundance), uranium-235 (235 U, 0.7198–0.7210%), and uranium-234 (234 U, 0.0049–0.0059%).
A 15x15 lattice-style grid is common for cryptic crosswords. A cryptic crossword is a crossword puzzle in which each clue is a word puzzle. Cryptic crosswords are particularly popular in the United Kingdom, where they originated, [1] as well as Ireland, the Netherlands, and in several Commonwealth nations, including Australia, Canada, India, Kenya, Malta, New Zealand, and South Africa.
Limonite (/ ˈlaɪməˌnaɪt /) is an iron ore consisting of a mixture of hydrated iron (III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO (OH)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the ...
Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper ores consists of a series of physical, chemical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors. [ 1 ]
Bessemer process. The Bessemer process was the first inexpensive industrial process for the mass production of steel from molten pig iron before the development of the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron. The oxidation also raises the temperature ...
Hematite (/ ˈ h iː m ə ˌ t aɪ t, ˈ h ɛ m ə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe 2 O 3 and is widely found in rocks and soils. [6] Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe 2 O 3. It has the same crystal structure as corundum ...