Some soil minerals, such as quartz
and rutile are resistant to HF-treatment (Skjemstad et al., 1994;
Gelinas et al., 2001), especially under the relatively gentle conditions
used here (low HF concentration, no added HCl, no heating).
However, these minerals tend to have low surface areas and therefore
are unlikely to interact strongly with the organic matter and
thereby affect its sorption properties.