珪けい岩がんけいがんMeanings1nounquartziteA hard metamorphic rock composed mainly of quartz, used in construction and industry.珪けい岩がんは非ひ常じょうに硬かたい岩がん石せきです。Quartzite is a very hard rock.この地ち域いきでは良りょう質しつな珪けい岩がんが採とれる。High-quality quartzite is mined in this region.