Moon rocks

Spherulites have been observed in organic and inorganic systems of synthetic, biological, and geological origin, including moon rocks, and are therefore not unique to polymers. 

Geological surveys require the services of analytical chemists to determine the composition of the numerous rock and soil samples collected in the field. A particular instance of such an exercise is the qualitative and quantitative examination of the samples of moon rock brought back to Earth in 1969 by the first American astronauts to land on the moon. 

It must be stressed, however, that the whole object may be the analytical sample, e.g. a specimen of moon-rock. Ideally this sample would be analysed by non-destructive methods. Occasionally the bulk material may be homogeneous (some water samples) and then only one increment may be needed to determine the properties of the bulk. This increment should be of suitable size to provide samples for replicate analyses. 

When a sample of moon rock was analyzed by mass spectroscopy, the ratio of K to Ar was found to be 0.1295. Based on this ratio, how old is the moon ... 

The first moon explorers brought back rock samples of a nature never before seen on earth, but they did not find any new elements. The moon rocks merely added to the proof that the moon, the earth, and the whole universe are made from the same elemental building blocks. 

The moon rocks brought back to earth are only a tiny sample of the moon s surface, but they are enough to show that some elements common on earth may be rare on the moon, and some that are rare here on earth may be common on the moon. So far, as on earth, oxygen and silicon seem to be the most common lunar elements. Early experiments have found more uranium and less potassium, more titanium and less sodium. Oxygen is strikingly absent from some minerals, but natural glass is far more common than it is on earth. The rare, noble gases are fairly abundant, trapped in little bubbles in the rocks. 

Titanium occurs in nature in the minerals rutile( Ti02), ilmenite (FeTiOs), geikielite, (MgTiOs) perovskite (CaTiOs) and titanite or sphene (CaTiSi04(0,0H,F)). It also is found in many iron ores. Abundance of titanium in the earth s crust is 0.565%. Titanium has been detected in moon rocks and meteorites. Titanium oxide has been detected in the spectra of M-type stars and interstellar space. 

The element was discovered in 1794 by the Swedish chemist Gadolin. He named it after the small town Ytterby in Sweden where the mineral containing yttria was found. Mosander in 1843 determined that the yttria consisted of three oxides yttria, erbia, and terbia. Yttrium occurs in all rare earths. It is recovered commercially from monazite sand, which contains about 3% yttrium. It also is found in bastnasite in smaller amounts of about 0.2%. Abundance of yttrium in earth s crust is estimated to be 33 mg/kg. The metal has been detected in moon rocks. 

A lunar expedition brought back some moon rocks. Analysis of the rocks showed them to contain 17% potassium-40 and 83% argon by mass. The half-life of K-40 is 1.2 x 10 years. K-40 decays through positron emission. Ar-40 is the decay product of the reaction. How old was the rock sample (in years) ... 

A popular method used to date rocks is the potassium-argon method. Potassium is abundant in rocks such as feldspars, hornblendes, and micas. The K-Ar method has been used to date the Earth and its geologic formations. It has also been applied to determine magnetic reversals that have taken place throughout the Earth s history. Another method used in geologic dating is the rubidium-strontium, Rb-Sr, method. Some of the oldest rocks on Earth have been dated with this method, providing evidence that the Earth is approximately 5 billion years old. The method has also been used to date moon rocks and meteorites. 

Warren, P. H. (1993) A concise compilation of petrologic information on possibly pristine nonmare Moon rocks. American Mineralogist, 78, 360-376. 

Information on the current arsenic content of the solar system is largely limited to spectrographic analyses of the Sun, Saturn, and Jupiter measurements on available Moon rocks and meteorites and analyses of terrestrial materials. Spectrographic analyses indicate that the arsenic concentration of the Sun is about 0.004 mg kg-1 (Matschullat, 2000, 299 Table 3.1). Arsenic is moderately volatile in the vacuum of space (McDonough, 2004, 555) and should be preferentially concentrated on Jupiter and other planets... 

On Earth, the Ti(m) oxidation state is unstable. However, Ti3+-bearing minerals are well-characterized in some meteorites and Moon rocks, generally coexisting with Ti4 in such phases as calcic pyroxene, ulvospinel, hibonite and ilmenite. In hibonite, CaAlI20I9, a refractory phase in carbonaceous chondrites, EPR and optical spectral data indicate that Ti3+ ions are present (Hunger and Stolper, 1986 Live et al., 1986). The trivalent Ti ions may be stabilized in the five-coordinated trigonal bipyramidal M5 site of the hibonite structure... 

Bums and Bums, 1984b). In Moon rocks, Ti3+/Ti4+ ratios might be expected to decrease in the order ilmenite > ulvospinel > pyroxene. 

Reflectance spectra of ferrous silicates in Moon rocks... 

Warren P. H. (1986) Anorthosite assimilation and the origin of the Mg/Fe-related bimodahty of pristine Moon rocks support for the magmasphere hypothesis. Proc. 16th Lunar Planet. Sci. Conf, D331-D343. 

Warren P. H., Jerde E. A., and Kallemeyn G. W. (1987) Pristine Moon rocks a large felsite and a metal-rich ferroan anorthosite. Proc. 17th Lunar Planet. Sci. Corf., E303-E313. 

The first footprint on the moon s surface, made by astronaut Neil A Armstrong on July 20,1969, shows the fineness of the lunar soitThesoil is produced when moon rock is weathered by impacting meteors, solar winds and extreme temperature changes. In many areas the soil appears to be a f i r meters thick. U.S. NationaS Aeronautics and Space Administration... 

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