Clinochlore and Muscovite in Quartz from Colorado
Recently the author encountered a parcel of quartz with phantom layers consisting of beautiful bluish green and white spheres (figure 1). Raman analysis identified the green spheres as clinochlore (figure 2), Mg5Al(AlSi3O10)(OH)8, a member of the chlorite group. Many of the white orbs appeared to be secondarily altered, presumably by fluids entering through fractures in the quartz host, though some showed no clear evidence of alteration. Raman analysis of one of the unaltered white spheres identified it as muscovite, KAl2(AlSi3O10)(OH)2. Minute dark brown to black spheres were also present and visually consistent with hematite, but that could not be confirmed by Raman analysis.
This material is from Larimer County, Colorado, where it was collected in 2020 by Nico Jackson. So far, three pockets of material have been discovered, with a total production of about 10 kg. While chlorite-group minerals are relatively common inclusions in quartz, the soft texture and greenish blue color of these clinochlore spheres are less common in the author’s experience. These green clinochlore spheres with contrasting white muscovite spheres are a striking addition to the possible minerals seen in the micro-world of quartz.