5.2 Sandstone ore appraisal
The sandstone ore appraisal is shown in Fig. 3. The sandstone is a
stratum under the Pen-laizhen group of late Jurassic. The sandstone is
of medium maturity and composed of detritus (84%) and fillings (16 %).
The detritus covers 62% quartz (Q), 10% plagioclase (Pl), 8%
K-feldspar (Kf), 2% mica, and 2% chlorite with good sorting and
psephicity; while the fillings include 4% mud and 12% calcite. The
grain-sizes are 0.08-0.25 mm.