石英 is read as せきえい (sekiei) and means quartz.
せきえい
sekiei
せきえいがらす
fused silica
しゅせきえい
cream of tartar
せきえいそめんがん
liparite
せきえいさ
quartz sand
ようゆうせきえい
fused quartz
にゅうせきえい
milky quartz
えいこくせきゆ
British Petroleum
いしがみ
stone which is worshipped
いしむろ
stone hut
いしだん
(flight of) stone steps
こく
measure of a Japanese-style boat's loading capacity (approx. 278.26 liters)
いし
flint (in a lighter)