High Incidence of Scandium and REY in Garnets from Coastal Sands of India

The economic heavy mineral suite in beach, dune and offshore sands of Odisha, Andhra Pradesh (AP), Tamil Nadu (TN) and Kerala coasts in India mainly comprises ilmenite, garnet, sillimanite, rutile, monazite and zircon. The garnet collected from Kalingapatnam coast, AP reported high incidence (point analysis by EPMA) of rare earth elements (REE) (1500–5300 ppm) especially HREE¹. EPMA of a few garnet grains collected off Anjengo, Kerala, also showed encouraging REE (1200–5000 ppm) values². Nine sand samples were collected from Taingapatnam, Nanjam, Manavalakurichi, Kanyakumari and Uvary in TN, and Santepalle, Bhavanapadu and Yarada in AP (Figure 1) from Indian coast to understand the REE concentrations in garnets. Among the nine, seven samples, viz. GRT-1 (ST-216), GRT-2 (ST-171), GRT-3 (ST-171), GRT-5 (SS-106), GRT-6 (SS-106), GRT-7 (SS-140) and GRT-8 (SS-140) were collected during cruises of Marine and Coastal Survey Division (MCSD), Geological Survey of India (GSI) and the remaining two samples, viz. GRT-10 and GRT-11 were collected from IREL Research Centre, Kollam and AMD, Thiruvananthapuram respectively. These samples contain economically important heavy minerals in different proportions and were subjected to multiple processes for enriching garnet at IREL Research Centre, Kollam, using REDMS (rare earth drum magnetic separator), CSS (corona static separator), EPS (electrostatic plate separator), IRMS (induced roll magnetic separator) and diiodomethane (3.3 specific gravity) to make the samples >95% enriched in garnet. The enriched garnet samples were subjected to HR-ICPMS and XRD analyses for trace elements and mineral phases respectively, at the National Institute of Oceanography (NIO), Goa.