EVALUATION OF VEIN QUARTZ, MONTGOMERY COUNTY, NORTH CAROLINA FOR ITS SUITABILITY AS A QUARTZ RESOURCE

Stock work vein quartz ~20 kg samples from metavolcanic rocks from Montgomery County, North Carolina, were evaluated for their quartz resource suitability. 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 Grade). The chemical analysis of the quartz concentrates before and after leaching is shown 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). 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 standard and fiber optical components. HPQ chips (lascas) are used in the manufacture of piezo-electric quartz crystals (cultured quartz). 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 shuttle. No gold was detected at the ppb level in three composite bulk samples or one duplicate bulk sample. The chemical composition (ppm) of the quartz is as follows: Mill Creek #1 (not leached): Al (15.4), Ca (15.6), Fe (5.26), K (1.57), Li (0.31), Na (14.70), Ti (0.31), Mg (0.21), Zr (0.29); Mill Creek #1 (leached): Al (12.0), Ca (7.57), Fe (0.08), K (1.23), Li (0.36), Na (10.80), Ti (0.17), Mg (0.09), Zr (0.01); Little River (not leached): Al (19.3), Ca (7.74), Fe (3.69), K (1.70), Li (0.25), Na (22.50), Ti (0.43), Mg (0.19), Zr (0.14); Little River (leached): Al (15.8), Ca (3.80), Fe (0.03), K (1.88), Li (0.67), Na (19.70), Ti (0.37), Mg (0.09), Zr (0.01).