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A rare-earth mineral contains one or more rare-earth elements as major metal constituents. Rare-earth minerals are usually found in association with alkaline to peralkaline igneous magmas in pegmatites or with carbonatite intrusives. Perovskite mineral phases are common hosts to rare-earth elements within the alkaline complexes.
^ Florida's state gem, moonstone, was adopted to highlight Florida's role in the United States' Lunar program, which landed the first astronauts on the Moon. [81] ^ Since 1983, Massachusetts has had 3 other official state rocks: State Historical Rock (Plymouth Rock), State Explorer Rock (Dighton Rock), and State Building and Monument Stone . In ...
Rare earths were mainly discovered as components of minerals. The term "rare" refers to these rarely found minerals and "earth" comes from an old name for oxides, the chemical form for these elements in the mineral. [16]: 5 A mineral discovered by Lieutenant Carl Axel Arrhenius in 1787 at a quarry in the village of Ytterby, Sweden.
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If diamonds are a girl’s best friend, 7-year-old Aspen Brown has a pal for life after finding an immense 2.95-carat brown diamond last week — while celebrating her birthday — at a state ...
Novaculite, also called Arkansas Stone, is a microcrystalline to cryptocrystalline rock type that consists of silica in the form of chert or flint. It is commonly white to grey or black in color, with a specific gravity that ranges from 2.2 to 2.5.
The Geological Survey of Arkansas was first established in 1857, at the direction of Governor Elias Nelson Conway. David Dale Owen was the agencies first geologist. Initially, the agency received funding for only three years, which limited the agencies findings and publications, and the agency was left without funding during the Civil War.
The macroscopic colour is grey, being little darker than granite. There is high-grade metamorphic rock originated from nepheline syenite that is characterized by gneiss texture of very rare occurrence. It is called nepheline syenite gneiss or litchfieldite. An example is found at Canaã village, State of Rio de Janeiro, Brazil.