出典:Wiktionary
quartzite (countable かつ uncountable, 複数形 quartzites)
出典:Wikipedia
出典:『Wikipedia』 (2011/07/08 22:11 UTC 版)
Quartzite (from German Quarzit) is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colors, such as yellow and orange, are due to other mineral impurities.