Characterization and Identification of Coal and Carbonaceous Shale Using Visible and Near-Infrared Reflectance Spectroscopy

Table 1

Spectral regions related to the major compositions [27–30].

No.	Absorption band (nm)	Major related interactive process	Selected wavelength region (nm)
1	400, 430, 450, 490, 510, 520, 550	Fe^2+ and Fe^3+ in ferriferous minerals	400–550
2	700	Fe^3+ in ferriferous minerals	650–750
3	870	Fe^3+ in ferriferous minerals	820–920
4	1000–1100	Fe^2+ in ferriferous minerals	1000–1100
5	1400	OH^− vibrations in clay minerals	1350–1450
6	1900	H2O vibrations in milky quartz	1850–1950
7	2200	Al–OH vibrations in clay minerals	2150–2250
8	2300–2500	Overtones and combinations of organic absorption groups	2300–2500