[DOC] [TLE] Peridotite - Wikipedia [PAR] Peridotite is a dense, coarse-grained igneous rock consisting mostly of the 
minerals olivine and ... The word peridotite comes from the gemstone peridot, 
which consists of pale green olivine. ... Certain volcanic rocks, sometimes called 
komatiites, are so rich in olivine and pyroxene that they also can be termed 
peridotite. [DOC] [TLE] GEM FORMATION [PAR] This gemiferous crust is made up of three types of rocks: igneous, sedimentary ... 
in an age-old, and continuing, recycling program of Nature called the "Rock 
Cycle". ... Granite and basalt are examples of larger and smaller grained igneous 
rocks, ... tectonic action may melt and form magma which produces igneous rocks
. [DOC] [TLE] Geology of Gems [PAR] When any pre-existing rock (called a protolith) is heated fluids already within ... 
Basalt, with increasing metamorphism, turns to greenstone and eventually ... take 
place if conditions are right, producing "metamorphic minerals" and rock .... 
Metamorphic rocks are typically the hardest to clearly identify for a variety of 
reasons. [DOC] [TLE] Minerals, Gems Information, Facts, News, Photos -- National ... [PAR] Minerals are typically formed when molten rock, or magma, cools, or by ... 
Silicatesincluding quartz, mica, olivine, and precious minerals such as ... 
Diamonds, made of carbon atoms, are the hardest natural substance found on 
Earth. ... Rubies are formed of a mineral called corundum, comprised of 
aluminum oxide. [DOC] [TLE] University of Minnesota's Mineral Pages: Olivine [PAR] Minerals in the Olivine Series are important rock-forming minerals in mafic ... of 
mafic igneous rocks, there really is no single mineral called olivine. ... a 
gemstone, peridot's beauty allows it to compete with harder gemstones like ... 
During metamorphism, olivine is altered to serpentine, which gives the 
metamorphic rock of the... [DOC] [TLE] Olivine: A rock-forming mineral. Used as the gemstone peridot. [PAR] Olivine is a green rock-forming mineral found mainly in dark-colored igneous 
rocks and ... That makes it one of the first minerals to crystallize from a magma. [DOC] [TLE] Corundum: Use as a Gemstone, Abrasive, Refractory - Geology.com [PAR] Corundum is a rock-forming mineral that is found in igneous, metamorphic, and 
sedimentary rocks. ... The extreme hardness makes corundum an excellent 
abrasive, and when that hardness ... A gemstone-quality corundum with a blue 
color is called a "sapphire. ... It is the third-hardest mineral, after diamond and 
moissanite. [DOC] [TLE] Volcanic Minerals - Volcano World [PAR] Volcanoes directly or indirectly produce or host deposits of aluminum, diamonds, 
... In some locations, deeply weather volcanic rocks, usually basalt , form .... 
Diamonds are crystalline carbon and the hardest known substance. .... The 
ancient volcanic hills called Glass Buttes hold a dazzling variety of gem-quality 
obsidian,... [DOC] [TLE] Diamond - The Mineral and Gemstone Kingdom [PAR] Complete Information Guide to Rocks, Minerals, & Gemstones ... Diamond is 
number 10 on the Mohs scale, and is 40 times harder than Corundum, which is ... 
Diamond exhibits great "fire" and brilliance, which gives it a shiny, freshly 
polished look. .... Olivine, Magnetite, Pyrope, Phlogopite, Graphite, Omphacite, (
Kimberlite)... [DOC] [TLE] Mining Part 2: Important Minerals, Gems, and Rocks Mined in North ... [PAR] Jan 1, 2006 ... Found as chromite (chromium oxide) in olivine-rich rock called dunite. ... The 
hardest known mineral, found only rarely in western North Carolina. ... North 
Carolina produces two-thirds of the nation's scrap mica, which found... [DOC] [TLE] Silicates, Rocks and Minerals, Kentucky Geological Survey [PAR] Olivine is a common igneous rock-forming mineral and occurs in both basaltic ... 
Transparent gem-quality varieties are known as peridots. ... Quartz is the hardest, 
most resistant mineral found in abundance in Kentucky. ... for example, iron gives 
a red or orange color and manganese or calcium give black or blue colors. [DOC] [TLE] Rubies & SapphiresSparkling Reminders

Question: A rock called pridotite produces this hardest gem
Answer: diamond