Minerals zircon, ZrSiO

Most important mineral Zircon ZrSiO (Figure M30). Some forms of zircon have excellent gemstone qualities. Baddeleyite ZrOj. The zirconium in nature contains 0.5-2 % hafnium. 

The mineral zircon ZrSiO is used for moulds in foundries. Its high thermal conductivity improves the coohng rate compared to other mould materials. Zirconium oxide is used in firebricks. It has very good temperature resistance and is, after sintering, also used for crucibles and other components for work at high temperatures. When zirconia is heated, a phase transformation occurs at a temperature of about 1200°C. 

The oxide can be manufactured from the mineral zircon by caustic fusion at 650°C. ZrSiO -I- 4NaOH Na ZrOj -i- Na SiOj + 2H O... 

Zirconium silicate (ZrSiO ) is one form of the mineral whose crystals when polished are known as cubic zircons, which resemble diamond gemstones. 

Occurrence.4 — The chief zirconium minerals are zircon, an orthiindicate, ZrSiO, tuul baddoloyite, Zr()2, with traces of... 

The metal zirconium is not as rare as might be expected. It is eighteenth in abundance in the earth s crust and more common than copper and zinc together. The most important mineral is zircon, zirconium silicate ZrSiO. Badddeyite, zirconium oxide ZrOj (Table 19.1) is also important There are, however, no zircon mines. Zircon is recovered as a by-product from the extraction of titanium from ores containing the minerals rutile and ilmenite. 

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