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Zircon


Zircon' brown, green, pale-blue, red, orange, golden-yellow, grayish or colourless neosilicate mineral occurring in tetragonal prisms. It is the chief source of zirconium; the colourless varieties provide brilliant gemstones. Also known as hyacinth, jacinth, zirconite. It shows conchoidal fracture and cleavage visible in one direction. Its hardness is 7 on Moh's scale. It occurs in granites, syenites, schists and crystalline limestones. Zircon is occasionally radioactive because of the presence of thorium and uranium, replacing zirconium in the structure. The presence of thorium and uranium makes it a useful mineral for the age determination of such rocks.

Table  Reserve of zircon at different localities in Bangladesh.

Locality Raw Sand Heavy Mineral Zircon
Badarmokam (Cox's Bazar) 1765000  411000 4932
Sabrang (Cox's Bazar) 347558 68582  4184
Teknaf (Cox's Bazar) 1939580  442291 28306
Shilkhali (Cox's Bazar) 2756828 489714 33300
Inani (Cox's Bazar) 729286 175476 10880
Cox's Bazar 5119000 920000 23000
Maheshkhali Island (Cox's Bazar) 4114230 784210 37112
Matarbari Island (Cox's Bazar) 69030 15215 794
Nijhum Island (Noakhali) 379337 96348 2052
Kutubdia Island (Cox's Bazar) 404646 120000 3900
Kuakata (Patuakhali) 2872486 831668 9647
Total 20496981 4354504 158117

Source Badrul Imam, Bangladesher Khaniz Sampad, 1996.

It is a principal source of zirconium and hafnium for industry and is extracted from sands, the most important sources being beach deposits. In Bangladesh zircon is found as beach sand heavy mineral placer deposits on the sea beaches and coastal islands of Cox's Bazar, Chittagong, Noakhali and Patuakhali districts. It occurs mostly with fine to very fine sand grains. Generally the sands containing it are even finer than the sands containing Ilmenite, garnet and Rutile. The highest concentration of zircon, reported from Shilkhali, is 7%, the lowest concentration is 1% and the average is 4%. The reserve of zircon in Bangladesh is about 158,117 thousand ton (see table with figures in tons). [Sifatul Quader Chowdhury]