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).