Dunite

Forsterite. Pure forsterite is rare in nature. Most natural magnesium orthosiUcates form soHd solutions of fayaUte, Fe2Si04, and forsterite. Forsterite refractories are usually made by calcining magnesium siUcate rock such as dunite, serpentine, or oHvine with sufficient magnesia added to convert all excess siUca to forsterite and all sesquioxides to magnesia spinels. 

Soil is a mixture of solid materials, air and, usually, water and organic matter. The radium content of soil often reflects that of the rocks from which the solid materials are derived by physical and chemical activity. The observed ranges are from 0 to 20 Bq kg for ultrabasic rocks (dunite) to 1 to 1835 Bq kg for igneous metamorphic rocks (gneiss) (Wollenberg, 1984). While these ranges are broader than those for measured for soils, the mean values for rocks, excluding alkali rocks, is consistent with the means observed for soils. 

The Expo Intrusive Suite is for the most part composed of mafic and ultramafic intrusions, shaped as tabular-shaped discordant bodies, so are referred as dykes. The Expo suite is economically important due to the presence of sulfide mineralization in the internal part of the intrusion. It is composed of gabbro norite, pyroxenite, peridotite, and dunite. 

Figure 9. Plots of Li and radiogenic isotopes for mantle rocks, (a) 5 Li vs. Sr/ Sr (b) 5 Li vs. Nd/ Nd (c) "Sr/ Sr vs. Pb/ Pb (d) 5"Li vs. Pb/ Pb (Nishio et al. 2003, 2004). Symbols + = south Pacific island basalts (six islands) O = Iherzolite xenolith, Bullenmerri, Australia = Iherzolite xenolith, Sikhote-Alin, Russia (three localities) A = dunite-peridotite-pyroxenite xenolith, Kyushu, Japan (two localities) V = Iherzolite xenolith, Ichinomegata, Japan. The ocean island data are from bulk rocks, the xenolith data are clinopyroxene separates. For explanations of the derivation of radiogenic isotope fields (DM, EMI, EM2, HIMU), see Zindler and Hart (1986). The estimate for Li isotopes in DM is based on MORE. The Li isotopic ranges for the other mantle reservoirs are based on Nishio et al. (2004) and Nishio et al. (2003), but these will require further examination (hence the use of question marks).

Layne GD (2003) Advantages of secondary ion mass spectrometry (SIMS) for stable isotope microanalysis of the trace light elements. EOS Trans, Am Geophys Union 84 F1635 Lundstrom CC, Chaussidon M, Kelemen P (2001) A Li isotope profile in a dunite to Iherzolite transed within the Trinity Ophiolite evidence for isotopic fractionation by diffusion. EOS Trans, Am Geophys Union 82 991... 

Misawa, K., Shih, C.-Y., Reese, Y., Bogard, D. D. andNyquist, L. E. (2006) Rb-Sr, Sm-Nd and Ar-Ar isotopic systematics of Martian dunite Chassigny. Earth and Planetary Science Letters, 246, 90-101. 

Chittendon, E.T., Stanton, D.J., Watson, J. and Hodgson, L. 1964. Serpentine and dunite as magnesium fertiliser. New Zealand Journal of Agricultural Research 10 160-171. 

Rocks consisting essentially of olivine alone are known as dunites, the name coming from the occurrence of this rock in the Dun mountains of New Zealand. In the United States, this mineral is found in North Carolina, South Carolina, and Georgia, where corundum is associated wtith the dunite in commercial quantities. The olivine of peridotites alters readily to the mineral serpentine, often to such an extent that the rock itself is called a serpentine. As mentioned above, the pendotites may contain chromite or other valuable minerals, often to such an extent that they may be commercially exploited, for nickel, platinum, and precious garneL... 

Ultramafics (Minnesota Peak, Alaska, USA, 2 samples) 6.5 34 Ultramafics (peridotite, dunite, and serpentinite) 0.3-15.8... 

Dunite An intrusive igneous rock that almost entirely consists of olivine, (Mg,Fe)2SiC>4. 

Cigolini C (1999) "High pressure" dunitic ejecta of kimberlitic affinity in recent pyroclastic deposits from Mount Vesuvius inference on their genesis and evolution. Atti Ace Sc Fis, Torino, 133 149-158... 

Mody VH, Durairaj A, MehraAO, Pharmacological approaches to prevent restenosis. In Faxon DR ed, Restenosis A Guide to Therapy. U.K. Martin Dunite, 2001 97— I 12. 

Staudacher, Th., Kurz, M. D., Allegre, C. J. (1986) New Noble-gas data on glass samples from Loihi seamount and Hualalai and dunite samples from Loihi and Reunion Island. Chem. Geol., 56, 193-205. 

Schulien, S., Homemann, U. Stoffler, D. (1978) Electrical conductivity of dunite during shock compression from 12.5 to 45 GPa. Geophys. Res. Lett., 5, 345-8. 

Prof. Dr. Jack D. Dunite Laboratorium fiir Organische Chemie der Eidgenossischen Hochschule UniversitatsstraBe 6/8, CH-8006 Zurich... 

Fig. 15.3. Crustose lichen Lecidea lactea growing on dunite, a rock composed of the silicate olivine ((Mg, Fe)2Si04). Note dark stain (arrowed) below lichen representing amorphous silica coated in iron produced by lichen weathering (Purvis, 2000).

Fitz Gerald, J. D., Chopra, P. N. (1982). Deformation mechanisms in dunite -the results of high temperature testing. In Strength of Metals and Alloys, edited by R. C. Gifkins, pp. 735-40. Oxford Pergamon Press. 

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