EVALUATION OF VEIN QUARTZ, MONTGOMERY COUNTY, NORTH
CAROLINA FOR ITS SUITABILITY AS A QUARTZ RESOURCE
MENSAH-BINEY, Robert, North Carolina State University’s Minerals
Research Laboratory, 180 Coxe Ave., Asheville, NC 28801, REID,
Jeffrey C., North Geological Survey, 1612 Mail Service Center, Raleigh,
Stock work vein quartz ~20 kg samples from metavolcanic rocks from
Montgomery County, North Carolina, were evaluated for their quartz
Preliminary processing evaluation and chemical analysis of the quartz
concentrates from the two samples indicated low impurity levels to
justify further chemical treatment to produce ultra-high purity quartz.
The processing steps involved crushing, grinding to produce 60 x 140
mesh, flotation to remove mica, iron minerals and feldspar impurities,
magnetic separation of the clean quartz, sizing and hydrofluoric /
hydrochloric acid leach to produce ultra-high purity quartz product (Iota
Above - Outcrop sample displays primary hydrothermal ‘plumbing’ and
The chemical analysis of the quartz concentrates before and after at least three generations of quartz.
leaching is shown in the table below (unleached product is after
magnetic separation, leached product is after leaching with HF/H2SO4).
Although chemical leaching resulted in significant reduction in Fe and
Mg, the impurity level for Al, Ca, Na, K was too high for ultra-high purity
quartz. Additional process evaluation is needed to remove additional
Al, Fe, Ca, K, and Na to produce high-pure quartz (Quintas Grade). Above – outcrop and outcrop detail of example quartz
exposure in Montgomery County, NC.
Granular high purity quartz (HPQ) is used in the manufacture of optical
glasses and for high purity silica glasses for semiconductor silicon in
silicon computer and memory chip production (high purity crucibles for
growing the silicon), for high intensity lighting applications and for
Below – location map showing location of Montgomery Co.
standard and fiber optical components. HPQ chips (lascas) are used in North Carolina and generalized geology from the ‘Geologic
the manufacture of piezo-electric quartz crystals (cultured quartz). Map of North Carolina’ (1985).
Some of the lower purity HPQs are used in the ceramic industry for
high heat intensity applications such as the heating tile for the space
The quartz composition is shown in the table below. No gold was
detected at the ppb level in three composite bulk samples or one
duplicate bulk sample.
Sample Leached Al Ca Fe K Li Na Ti Mg Zr
Left – table shows chemical analysis before and after
(ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
Mill Creek #1 Unleached 15.4 15.6 5.26 1.57 0.31 14.7 0.31 0.21 0.29
Mill Creek #1 Leached 12 7.57 0.08 1.23 0.36 10.8 0.17 0.09 0.01
Little River Unleached 19.3 7.74 3.69 1.7 0.25 22.5 0.43 0.19 0.14
Little River Leached 15.8 3.8 0.03 1.88 0.67 19.7 0.37 0.09 0.01