EVALUATION OF THE BAKERSVILLE ECLOGITE, MITCHELL COUNTY, NORTH CAROLINA FOR ITS SUITABILITY AS AN ABRASIVE-GRADE GARNET

The bench scale laboratory process consisted of crushing, grinding, and gravity separation to separate the heavy minerals from the light minerals.  The sample was ground to pass US 30-mesh and the minus 30-mesh fraction was subjected to sink float separation using a heavy liquid with density of 2.96 g/cc.   The sink fraction (heavy mineral concentrate) composed mainly of garnet was subjected to mineralogical evaluation to determine garnet grade. The results of the heavy liquid separation process indicated that about 85% by weight of the original material reported as heavy mineral concentrate.

The garnets are red, subhedral, and average 2 mm in diameter. Microprobe compositions are Py₃₂Alm₄₇Grs₂₂Sps_<1 [rims] and Py₂₇Alm₄₉Grs₂₄Sps_<1 [cores] (Willard and Adams, 1994).

DRY PARTICLE SIZE ANALYSIS OF GARNET - (+ 200 MESH SINKS)
Particle Size			Weight		Weight		Cum. %		Cum. %
US, mesh	microns		g		%		Retained		Passing
16	1180		0.10		0.1		0.1		99.9
30	595		7.40		8.3		8.4		91.6
40	420		20.50		23.1		31.5		68.5
50	300		18.80		21.2		52.7		47.3
60	250		7.90		8.9		61.6		38.4
100	150		17.30		19.5		81.1		18.9
Pan	-150		16.80		18.9		100.0
Total			88.80		100.0

Reference - Willard, R.A., and Adams, M.G., 1994, Earth and Planetary Science Letters, v.123, pp. 61-70.