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Decomposed granite is a kind of granite rock that is weathered to the point that the parent material readily fractures into smaller pieces of weaker rock. Further weathering yields material that easily crumbles into mixtures of gravel -sized particles known as grus that further may break down to produce a mixture of clay and silica sand or silt ...
First found in the United States, unakite has a worldwide distribution, having also been reported in South Africa, Sierra Leone, Brazil, China, India and Australia. Some material labeled unakite lacks the feldspar and is more properly called epidosite , and is also used as beads and cabochons .
Granite (/ ˈ ɡ r æ n ɪ t / GRAN-it) is a coarse-grained intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous ...
In 1986, California named benitoite as its state gemstone, a form of the mineral barium titanium silicate that is unique to the Golden State and only found in gem quality in San Benito County. [ 80 ] ^ Colorado is the only state whose geological symbols reflect the national flag's colors: red (rhodochrosite), white (yule marble), and blue ...
This is a list of gemstones, organized by species and types. Minerals. There are over 300 types of minerals that have been used as gemstones. Such as: A–B
Bahia Emerald [2]; Carolina Emperor, [3] [4] 310 carats uncut, 64.8 carats cut; discovered in the United States in 2009, resides in the North Carolina Museum of Natural Sciences, Raleigh, NC, US
Llanite, which is similar to granite, is very strong, with a crushing strength of 37,800 lb/in 2 or 26,577,180 kg/m 2. [4] The mineral is also very similar in appearance to pietersite . [ citation needed ]
Jet is found in two forms, hard and soft. [5] Hard jet is the result of carbon compression and salt water; soft jet may be the result of carbon compression and fresh water. [5] Despite the name they both occupy the same area of the Mohs scale with the difference being that soft jet is more likely to crack when exposed to changes in temperature. [6]