Zhèzhǒng kuàngwùzhì zài hǎishuǐ zhōng de nóngdù yuē wéi bǎiwànfēnzhīyī.
The concentration of this mineral in seawater is approximately one millionth.
Tips
grammar
Chinese fractions follow the pattern X分之Y meaning Y out of X (lit. X-divided-of-Y). So 百万分之一 = one out of one million. Similarly: 三分之一 = one third, 百分之一 = one percent.
