Assertion: peat's composition | /r/HasProperty | classed as secondary mineral
Facets:
Source sentences:
text: Before the advent of X-ray diffraction clay was thought to be very small particles of quartz, feldspar, mica, hornblende or augite, but it is now known to be (with the exception of mica-based clays) a precipitate with a mineralogical composition that is dependent on but different from its parent materials and is classed as a secondary mineral.