Mineralogical compositions of coal gangues in various countries^2,7.

Mineral	Belgium	Czech Republic	Germany	Spain	Britain	Russia	China
Illite	80	10–45	41–66	20–60	10–31	5–30	10–30
Kaolinite	12	20–45	4–25	3–30	10–40	1–60	10–67
Chlorite	5	0–15	1–3	0–7	2–7		2–11
Quartz	8	10–50	13–27	5–57	15–25		15–35
Iron ore	0.5	0–25	0.5–5		2–10	0.2–8	2–10
Organic matters	10	0–25	5–10	4–30	5–25	8–40	5–25