In terms of chemical computation composition, in minerals with carbon, its surface carbon content is more than 40%.

煤系黄铁矿在化学计量组成中含有碳的矿物，其表面的含碳量均大于40%。

youdao

The results indicate that the content of carbon is about 90%, the degree of graphitization is 66% and the carbon of simple substance phase at the surface is 54%.

结果表明纳米石墨中碳含量为90%左右，石墨化度为66%，表面碳原子以碳单质状态存在的占54%。

youdao

Surface soil samples were collected in the deserts and Gobi regions of China. The carbonate content and carbon and oxygen isotopic composition were analyzed.

在中国的主要沙漠和戈壁等粉尘源区采集了地表沙或土壤（统称为表土）样品，分析了样品的碳酸盐含量和碳酸盐的碳氧同位素组成。

youdao