圧し石[oshiishi] stone weight
一石[isseki] one game (of go)
一石二鳥[issekinichou] killing two birds with one stone
英国石油[eikokusekiyu] British Petroleum
下石[shitaishi] nether millstone

化粧石鹸[keshousekken] toilet soap
化石[kaseki] fossil
化石学[kasekigaku] paleontology
化石層[kasekisou] fossil bed
化石燃料[kasekinenryou] fossil fuel

一閃[issen] flash
閃かす[hiramekasu] to brandish
閃き[hirameki] flair
閃く[hirameku] to flash (lightning, etc.)
閃光[senkou] flash

閃光電球[senkoudenkyuu] flash bulb
花崗閃緑岩[kakousenryokugan] granodiorite
紫電一閃[shidenissen] flash of lightning
電光一閃[denkouissen] flash of lightning
閃緑岩[senryokugan] diorite (a type of rock similar to granite)