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CATEGORY: geology
DEFINITION: A high-quality chert or agate often used as raw material for the manufacture of stone tools. It is an opaque, fine-grained or dense variety of the silica mineral that is mainly brick red to brownish red. Jasper has long been used for jewelry and ornamentation, has a dull luster but takes a fine polish. Its hardness and other physical properties are those of quartz.

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