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A cinder is a pyroclastic material. Cinders are extrusive igneous rocks. Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water. Cinder is typically brown, black, or red depending on its chemical content. A more modern name for cinder is Scoria. ==Characteristics== The following geologic characteristics define a cinder: *Uncemented *Vitric *Having bubble-like cavities, called vesicles *Measuring not less than 2.0 millimeters in at least one dimension *Apparent specific gravity between 1.0 and 2.0 *Typical cinders are red or black in color. *Contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cinder」の詳細全文を読む スポンサード リンク
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