HEAVY MINERAL DIAGNOSIS OF RAS BAGHDADY BLACK BEACH SAND: ACCUMULATIONS AND SIGNIFICANCE

A total of 30 samples each weighs 5 kg were collected from digging boreholes at 2 m depth at constant intervals across three profiles from Ras Baghdady beach sands, Red Sea coast, Egypt. Sieving, heavy mineral separation using Wilfy Shaked table and heavy liquid, magnetic separation using Lift type separator, mineral picking, mineral identifications, XRD, EDX and BSE have been performed to reveal the different mineral groups and the economic potentials. The separated grain size sub-samples arranged in their p order of abundance are 0.25-0.125 mm (10-60%), 0.5-0.25 mm (<10 to 20%), and 0.125-0.063 mm (<5 to 10%). Moreover, less than 1% to 10% are randomly distributed between grain size fractions < 0.063 and 1-0.5 mm. The most promising fraction based on the microscopic investigations containing mineral varieties and groups is very fine sand size. 60 gm of pure heavy minerals produced from 600 gm very fine sand size (0.125-0.063 mm). The light minerals are mainly detrital quartz grains and feldspars with mica flakes while the heavy minerals submitted to magnetic separation. Four separated magnetic sub-fractions (magnetite, ilmenite I, ilmenite II and ilmenite III) and one non-magnetic sub-fraction are obtained. The separated heavy minerals from Ras Baghdady very fine sand size (0.125-0.063 mm) contain 90 % of green silicates and 10 % of other heavy minerals in which ilmenite reaches 52 %, magnetite up to 15 %, garnet up to 11 %, goethite up to 11 %, zircon up to 5 %, rutile up to 3 %, sphene up to 3 % and other recorded traces of combined minerals up to 2 %. Based on the stereoscopic vision, XRD, BSE and SEM investigations, most of the studied heavy mineral grains are angular to sub-angular and homogenous in composition with a few variations to reflect short distance transportation and low energy deposition as depicted from the magnetically separated ilmenite grade III. The relative abundance and lateral distribution of the economic heavy mineral assemblages in the studied area are mainly controlled by hydraulic effects and beach topography. The estimated reserve of the economic heavy minerals within Ras Baghdady beach very fine sand can be summed up as follows; ilmenite 23490 tons, magnetite 6710 tons, garnet 5070 tons, goethite 5140 tons, zircon 2170 tons, rutile 1220 tons, sphene 1490 tons and leucoxene 10 tons. In addition to first record of ruby and sapphire, rare metal and radioactive bearing minerals such as monazite in which rare earth elements range is 61.2%, ~ 6.70 % Th, and ~ 5.4 % U as well as high content of Nd (17. 3%) and Sm (4.37%) are also recorded. Furthermore, the semi-quantitative EDX analyses of the picked uranothorite grains show high content of Th (40.12 %), U (11.77 %), and Y (11.9 %) while xenotime contains high content of Y2O3 (25.53 %), Yb2O3 (4.97 %), Nd2O3 (4.19 %) and Ce2O3 (3.46 %) as well.