Please look at the two columnar minerals adjacent to the calcite and chalcedony. The unknown mineral was circled by the red ellipse. The first picture is under plane polarized light, second under crossed nicols.
Note: This is from an intermediate sulfidation epithermal deposit.
Thank you all in advance.
I interpret the colorless mineral grains as quartz crystals. I interpret the growth-generation sequence as follows: The oldest formation is the radially-grown chalcedony (stained by hematite). This chalcedony is partially corroded by the quartz crystals. The latest growth generation is calcite, which fills the interstices in chalcedony and quartz. The calcite partially corrodes the quartz crystals at their upper ends, which show strong fretting.
Best regards,
Guenter Grundmann
I think the minerals adjacent to the calcite is quarts but its relief and form make me not to be sure. Also, the near cloudy appearance in PPL make me suspect orthoclase
Dear Guenter and Kayode,
Thank you for your answers. After my further confirmation, the unknown mineral is quartz. The odd, gray interference color of quartz is due to the position. In my study area, hematite is a common stained mineral in quartz, which made quartz not so clean.
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