Zirconium abundance

Fraser G., Ellis D., and Eggins S. (1997) Zirconium abundance in granulite-facies minerals, with implications for zircon geochronology in high-grade rocks. Geology 25, 607-610. 

Figure Bl.25.9(a) shows the positive SIMS spectrum of a silica-supported zirconium oxide catalyst precursor, freshly prepared by a condensation reaction between zirconium ethoxide and the hydroxyl groups of the support [17]. Note the simultaneous occurrence of single ions (Ff, Si, Zr and molecular ions (SiO, SiOFf, ZrO, ZrOFf, ZrtK. Also, the isotope pattern of zirconium is clearly visible. Isotopes are important in the identification of peaks, because all peak intensity ratios must agree with the natural abundance. In addition to the peaks expected from zirconia on silica mounted on an indium foil, the spectrum in figure Bl. 25.9(a)...

Zirconium is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analysis of lunar rock samples obtained during the various Apollo missions to the moon show a surprisingly high zirconium oxide content, compared with terrestrial rocks. 

Zirconium occurs naturally as a siUcate in zircon [1490-68-2] the oxide baddeleyite [12036-23-6] and in other oxide compounds. Zircon is an almost ubiquitous mineral, occurring ia granular limestone, gneiss, syenite, granite, sandstone, and many other minerals, albeit in small proportion, so that zircon is widely distributed in the earth s cmst. The average concentration of zirconium ia the earth s cmst is estimated at 220 ppm, about the same abundance as barium (250 ppm) and chromium (200 ppm) (2). 

Titanium, which comprises 0.63% (i.e. 6320 ppm) of the earth s crustal rocks, is a very abundant element (ninth of all elements, second of the transition elements), and, of the transition elements, only Fe, Ti and Mn are more abundant than zirconium (0.016%, 162 ppm). Even hafnium (2.8 ppm) is as common as Cs and Br. 

Table 21.1 summarizes a number of properties of these elements. The difficulties in attaining high purity has led to frequent revision of the estimates of several of these properties. Each element has a number of naturally occurring isotopes and, in the case of zirconium and hafnium, the least abundant of these is radioactive, though with a very long half-life ( Zr, 2.76%, 3.6 x 10 y Hf, 0.162%, 2.0 X 10 5 y). 

Zirconium (Zr) occurs in the lithosphere to the extent of 0.022% [1], Although it is much less abundant than Ti (0.63 %), it is roughly as abundant as C. Despite some technical difficulties in the production of pure Zr compounds, requiring separation of Hf-containing contaminants, it is one of the least expensive transition metals. Some of its fundamental... 

Example The high-resolution spectrum in the molecular ion range of a zirconium complex is typified by the isotopic pattern of zirconium and chlorine (Fig. 3.22). Zr represents the most abundant isotope of zirconium which is accompanied by Zr, r, Zr and Zr, all of them having considerable abun-... 

Zirconium can be a shiny grayish crystal-Uke hard metal that is strong, ductile, and malleable, or it can be produced as an undifferentiated powder. It is reactive in its pure form. Therefore, it is only found in compounds combined with other elements—mosdy oxygen. Zirconium-40 has many of the same properties and characteristics as does hafhium-72, which is located just below zirconium in group 4 of the periodic table. In fact, they are more similar than any other pairs of elements in that their ions have the same charge (+4) and are of the same general size. Because zirconium is more abundant and its chemistry is better known than hafnium s, scientists extrapolate zirconium s properties for information about hafnium. This also means that one twin contaminates the other, and this makes them difficult to separate. 

Zirconium is not a rare element. It is found over most of Earth s crust and is the 18th most abundant element, but it is not found as a free metal in nature. 

Fig. 5.5. Decomposition of Solar System abundances into r and s processes. Once an isotopic abundance table has been established for the Solar System, the nuclei are then very carefully separated into two groups those produced by the r process and those produced by the s process. Isotope by isotope, the nuclei are sorted into their respective categories. In order to determine the relative contributions of the two processes to solar abundances, the s component is first extracted, being the more easily identified. Indeed, the product of the neutron capture cross-section with the abundance is approximately constant for aU the elements in this class. The figure shows that europium, iridium and thorium come essentially from the r process, unlike strontium, zirconium, lanthanum and cerium, which originate mainly from the s process. Other elements have more mixed origins. (From Sneden 2001.)... 

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. 

Hafnium had lain hidden for untold centuries, not because of its rarity but because of its dose similarity to zirconium (16), and when Professor von Hevesy examined some historic museum specimens of zirconium compounds which had been prepared by Julius Thomsen, C. F. Rammelsberg, A. E. Nordenskjold, J.-C. G. de Marignac, and other experts on the chemistry of zirconium, he found that they contained from 1 to 5 per cent of the new element (26, 27). The latter is far more abundant than silver or gold. Since the earlier chemists were unable to prepare zirconium compounds free from hafnium, the discovery of the new element necessitated a revision of the atomic weight of zirconium (24, 28). Some of the minerals were of nepheline syenitic and some of granitic origin (20). Hafnium and zirconium are so closely related chemically and so closely associated in the mineral realm that their separation is even more difficult than that of niobium (columbium) and tantalum (29). The ratio of hafnium to zirconium is not the same in all minerals. 

Setser, J. L., and W. D. Ehmann Zirconium and hafnium abundances in meteorites, tektites and terrestrial materials. Geochim. cosmochim. Acta 28, 769-782 (1964). 

The abundances of the elements of the titanium group were compared to those of the zinc group in Table 13-1. It will be recalled that unlike the zinc group metals, which are rare but easily isolated, the titanium group metals are abundant, but purified with difficulty. Note from the (very rough) figures given that titanium is 50 times as abundant as zinc, zirconium is 3000 times as abundant as cadmium, and hafnium 30 times as abundant as mercury. 

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. 

I was born in Paris but as I said we moved soon in Thann, in Alsace and we lived in a villa within the walls of the factory. When the wind was blowing from the east, it smelled chlorine. From the west, it smelled sulfur dioxide. My friends and I played in the wooden frame of lead chambers that had been built by M. Gay-Lussac and were still used to produce sulfuric acid. I was always interested in plants and insects, which were abundant in the small woods and the meadows adjoining the villa. My father was very generous and absurdly confident in letting my sister and me, and all our friends, do all kinds of things that would be stricdy forbidden now. We played with sulfuric acid or zirconium bars, with mercury droplets, I visited all the workshops, there were not even gates to hinder entrance and the workers and the engineers were our friends. Today, this would be inconceivable. 

Ca) (iii) the nuclear statistical equilibrium peak at the position of Fe and (iv) the abundance peaks in the region past iron at the neutron closed shell positions (zirconium, barium, and lead), confirming the occurrence of processes of neutron-capture synthesis. The solar system abundance patterns associated specifically with the slow (s-process) and fast (r-process) processes of neutron capture synthesis are shown in Figure 2. 

Limitations, (i) As with other radionuclide-based ages, the terrestrial age of the sample must be known, (ii) Concentrations of Kr are quite low in most meteorites, typically just 5 X 10 atomg in chondrites. For this reason, Kr measurements are still scarce and their uncertainties can be relatively large, often —20%. (iii) Production rates for krypton isotopes may vary with the abundances of rubidium, yttrium, and zirconium relative to strontium. It should be understood that the original basis for the calculation of Pgi/Fgs was a set of relative cross-section measurements for the production of krypton from silver (Marti, 1967). 

The refractory component comprises the elements with the highest condensation temperatures. There are two groups of refractory elements the refractory lithophile elements (RLEs)—aluminum, calcium, titanium, beryllium, scandium, vanadium, strontium, yttrium, zirconium, niobium, barium, REE, hafnium, tantalum, thorium, uranium, plutonium—and the refractory siderophile elements (RSEs)—molybdenum, ruthenium, rhodium, tungsten, rhenium, iridium, platinum, osmium. The refractory component accounts for —5% of the total condensible matter. Variations in refractory element abundances of bulk meteorites reflect the incorporation of variable fractions of a refractory aluminum, calcium-rich component. Ratios among refractory lithophile elements are constant in all types of chondritic meteorites, at least to within —5%. 

The constancy of refractory element ratios in the Earth s mantle, discussed before, is documented in the most primitive samples from the Earth s mantle. Figure 8 plots (modified from Jochum et ai, 1989) the PM-normalized abundances of 21 refractory elements from four fertile spinel Iherzolites. These four samples closely approach, in their bulk chemical composition, the primitive upper mantle as defined in the previous section. The patterns of most of the REEs (up to praseodymium) and of titanium, zirconium, and yttrium are essentially flat. The three... 

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