| rock crystal |
a clear quartz used in making electronic and optical equipment
출처: wordnet.princeton.edu/perl/webwn
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| rock crystal |
quartz; a transparent form of silicon dioxide (silica), SiO 2 ; used for lenses.
출처: www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspz...
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| rock crystal |
Quartz is the second most abundant mineral in the Earth's crust. It has a hexagonal crystal structure made of trigonal crystallized silica (silicon dioxide, SiO2), with a hardness of 7 on the Mohs scale. Density is 2.6 g/cm³. The typical shape is a six-sided prism that ends in six-sided pyramids, although these are often distorted, or so massive that only part of the shape is apparent from a mined specimen. ...
출처: en.wikipedia.org/wiki/Rock_crystal
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