A light, porous, glassy lava, used in solid form as an abrasive and in powdered form as a polish and an abrasive.是什么意思_A light, porous, glassy lava, used in solid form as an abrasive and in powdered form as a polish and an abrasive.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句