Changes in low angle reflection (00l) of discrete clay minerals with ethylene glycol and thermal treatments. Positions of d-spacing (A) are approximate.

Mineral	Air-dried	Ethylene Glycol	*300–350 °C	*Temperature of collapse	Comments
Imogolite	20-12	20-12 A	19 A	300-450° C	Broad band
Kaolinite	7.15 A	7.15 A	7.15 A	500-550° C
Halloysite	10 A	10 A	7.2 A	450-520° C	Dehydrates irreversibly to 7A at 50° C
Serpentine	7.1 A	7.1 A	7.1 A	575-700° C	Broad 11-14A reflection at 550-600° C
Illite	10 A	10 A	10 A sharpens	700 – 900° C
Na-Smectite	12.5 A	17 A	10 A	800-1000° C	Trioctahedral may be stable up to 1000°
Ca-Smectite	15 A	17 A	10 A	800-1000° C	Trioctahedral may be stable up to 1000°
Mg-Chlorite	14 A	14 A	14 A	800° C	14 A increases at 500° C
Fe-Chlorite	14 A	14 A	14 A	550-600° C	14 A increases at 500° C
Vermiculite	14 A	14 A	10 A	800-1000° C
Palygorstite	10.5 A	10.5 A	10.5, 9.5 A	700-800° C	10.5 A intensity increase 150°C
Sepiolite	12.2 A	12.2 A	12.2, 10.5	700-800° C

* Temperatures where changes occur are dependent upon such factors as crystal sizes, the duration of heating, and chemical substitutions.