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|
|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|
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]