Zirconium minerals

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. 

Mineral Formula Cr)istal form Densit)r g/cm Hardness ) Color 

Baddeleyite ZrOj Monoclinic, prismatic 5.7-6.0 6.5 Brown to black 

The most abundant Zr mineral is zircon, ZrSi04, a tetragonal orthosilicate, frequently found in a prismatic, pyramidal habit, with Zr coordinated to eight oxygen atoms. A relatively common oxide is baddeleyite, Z1O2, a monoclinic mineral found in prismatic habit Other less common minerals are calzirtite, CaZrjTiO, and zirconolite, CaZrjTijOy, where zirconium appears associated with calcium and titanium. All these minerals can be found as primary or secondary. Hafnium is a common substituent for Zr, and rare earths such as yttrium are also found. 

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It was finally identified in zircon from Norway, by means of X-ray spectroscope analysis. It was named in honor of the city in which the discovery was made. Most zirconium minerals contain 1 to 5 percent hafnium. 

For papers on the analysis and examination of hafnium and zirconium minerals by x-ray emission, see the following references listed in Appendix VI 68, 86. 

George de Hevesy (1885-1966 Nobel Prize for chemistry 1943) and Dirk Coster (1889-1950). The search for this element was long, and it was eventually found as a companion of zirconium minerals by means of X-ray spectroscopy. 

ORIGIN OF NAME The name "zirconium" was derived from the Arabic word zargun, which means "gold color." Known in biblical times, zirconium mineral had several names (e.g., jargoon, jacith, and hyacinth). Later, the mineral was called "zirconia," and the element was later named "zirconium."... 

Zirconium is found in small amounts widely spread throughout nature, occurring in many alluvial deposits of lake and stream beds and ocean beaches. The most important mineral is zircon, or zircon orthosilicate, ZrSi04. Other zirconium minerals are eudialite, (Na, Ca, FeleZrSieOislOH, Cl), and baddeleyite, Zr02. It also occurs in monazite sand. The abundance of zirconium in the earth s crust is estimated as 165 mg/kg. 

Zirconium minerals are widely distributed in Nature, and have been used for centuries. In his enraptured description of the four-square city, Saint John the Divine mentioned the jacinth (or hyacinth) as one of the twelve precious stones that garnished the foundations of the city wall (14). 

Zirconium comprises 0.016% (162 ppm) of the Earth s crast and, as a transition element, is only less abundant than Fe, Ti, and Mu. Hafnium is much less abundant at 2.8 ppm, but is stUl comparable in quantity to Cs and Br. The most important minerals of zirconium are zircon (ZrSi04), which is mostly mined in Australia, South Africa, the USA, and Sri Lanka, and baddeleyite (Z1O2), found mostly in Brazil. The estimated reserves exceed a billion tonnes. Australia and South Africa account for about 80% of zircon mining. All zirconium minerals are contaminated by small quantities of hafnium (0.5-2% of Zr content), but in a few (such as alvite, MSi04 XH2O, M = Hf, Zr, Th) the content of Hf is comparable with that of Zr. The above-mentioned similarities in the chemical behavior of these metals explain their close association in Nature and the similarity of their isolation procedures. 

Hafnium is closely similar to zirconium, and natural zirconium minerals usually contain a few percent of hafnium. The element was not discovered until 1923, and it has found little use. 

Hafnium, predicted from atomic number sequence, was the first element to be discovered by X-ray methods. Coster and Hevesy (1923) looked for and found it in zirconium minerals which usually contain about 0.1%, but occasionally up to 7%. Because of its very close resemblance to zir-... 

ZrSi04) and baddeleyite, or zirconia or zirconium oxide (Zr02). The amount of zirconium produced in the United States is not reported. That information is regarded as a trade secret. As of 2008, the largest suppliers of zirconium minerals in the world are Australia and South Africa. These two countries produce about 72 percent of the world s zirconium. 

The Thoron method has been used for determining Th in plants [97], monazite sands and concentrates [9,30,31,98,99], silicate minerals [4,8,100], ores [101], zirconium minerals [49], and lanthanide compounds [42,44,102]. The froth flotation technique has been applied in the separation of Th from monazite sands [99],... 

Arsenazo HI was applied in the determination of thorium in biological materials [103,104], natural waters [34,105,106], fertilizers [107], glass [108], silicate minerals [2,10,27,55,109], niobium and tantalum minerals [110], uranium minerals [3,18], manganese ores [19], lanthanide compounds [26,44], zirconium minerals [111], titanium concentrates [111], ilmenite and rutile [112]. Thorium was determined in waters with the use of the FIA technique [106]. 

The structure of the zirconium mineral weloganite (Srj gCao 2)ZrNa2(C03)g,-3H2O has been determined by X-ray diffraction. Six carbonate groups and three water molecules are linked by three Sr ", one Zr, and two Na" ions. 

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

The production of zirconium minerals has never been extensive, nor has the supply been uniform. The United States production has come almost entirely from the North Carolina deposit, which rarely produces more than a ton per year, though in 1883, 26 tons were reported. The exportation from Brazil also shows a wide fluctuation, varying from 7 tons in 1903, to 1119 in 1913, and 8 tons in 1915. The demand during 1920 was brisk, due to increasing interest in zirconia. During the first half of the year zirkite ranged in price from 4 to 7 cents per pound wholesale, but during the latter part of the year the price fell to 3 to 4 cents per pound. 

Zirconium is the eleventh most abundant element in the earth s crust, which contains 0.028 percent of this element. It is more abundant than copper, lead, nickel, or zinc. Zirconium minerals always contain from 0.5 to 2 percent of chemically similar hafnium, which seldom occurs naturally by itself. 

Coster and Hevesy were thus encouraged to search amongst the zirconium minerals for the elusive element and in 1923 announced its presence as evidenced by its X-ray spectrum. They called the metal hafnium after Hafnia or Copenhagen. It was found to be present in varying amounts in most zirconium minerals, being about one-tenth as abundant as zirconium. Alvite (Zr, Hf, Th) Si04 was found to be particularly rich. 

Hafnium is dispersed in the Earth s crust to the extent of three parts per million, and is invariably found in minerals of zirconium up to a few percent compared with zirconium. Hafnium vapor has been identified in the Sun s atmosphere. Commercial sources of hafnium-bearing zirconium minerals are found in beach sands and river gravel in the United States (principally Florida), Australia, Brazil, western Africa, and India. Hafnium is concentrated in the upper horizons in a weathering profile of gabbroic rocks (Serpa, Portugal) ranging between 1.0 and... 

Zirconium oxide closely resembles aluminium oxide or alumina. For a long time the latter effectively concealed the presence of the former. Nobody suspected an unknown element in zirconium minerals known as early as the Middle Ages. Thus, zirconium, one of the most abundant metals on Earth (0.02%) remained invisible up to the end of the 18th century. Today the mineral zircon is the main source of zirconium it occurs in two varieties hyacinth and jargoon. Already in old times hyacinth was known as a precious stone owing to its beautiful colours ranging from yellow-brown to smoky green. 

In 1911, the French chemist G. Urbain is said to have discovered the chemical element with atomic number 72 in a rare earth residue, and he gave it the Latin name Celtium. Later, hafnium was thought to be present in various zirconium minerals and at various concentrations... 

Fitzpatrick, R. W., and D. J. Chittleborough. 2002. Titanium and zirconium minerals. In Soil Mineralogy with Environmental Applications, ed. J. B. Dixon and D. G. Schulze, 667-690. Soil Science Society of America Book Series 7. Madison, WI Soil Science Society of America. 

According to the first rule a hafnium ion with radius 0.72 A can substitute for a zirconium ion, radius 0.73 A. Bohr predicted that hafnium might well be found concealed in zirconium, and hafnium was indeed discovered in a Norwegian zirconium mineral at Bohr s institute in Copenhagen. This is descrihed in Chapter 20 Hafnium. 

Zircon occurs in silica-rich igneous rocks, particularly granite and pegmatite, and also in metamorphic and sedimentary rocks but rarely in workable concentrations. In spite of that, zircon is the dominant commercial zirconium mineral. Weathering and... 

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