Quartz, Cwn Fron.  (CWO)

Quartz, Cwn Fron. (CWO)

Quartz, SiO2. Cwm Fron mine, Nr. Tylwych, central Wales. At first glance this seam fragment appears to be calcite, but on testing and closer inspection,it is quartz. Very irregular intergrown prismatic crystals, some with darkened cores.