Table 1. Cr(VI) and total Cr content for the different samples.

Sample	Color	Source	Particle size μm	The amount of Cr(VI) (mass ratio m/m)	The amount of total Cr (mass ratio m/m)
1	Yellow	Kunming	<150	0.71%	2.2%
2	Green	Qujing	<150	0.72%	2.0%
3	Green	Qujing	250–830	0.85%	1.9%