shí yàn yuán / zài / bái sè / cí bǎn / shàng / mó cā / kuàng wù / guān chá / tā / liú xià / de / tiáo hén / yán sè

实验员在白色瓷板上摩擦矿物，观察它留下的条痕颜色。

The lab technician rubbed the mineral on a white porcelain plate to observe the color of the streak it left.