ballstone
n. [地质] 球石
例句
Quartz, zircon, magnetite, gold are major constituents of littoral placers in Shandong province, while shell, ballstone, ilmenite, rutile being secondary.
山东省滨海砂矿以石英、锆英石、磁铁矿、砂金等为主,其次为贝壳、球石、钛铁矿、金红石等。