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“It may not be generally known that an ordinary horseshoe magnet when drawn over a piece of magnetite (best over a smooth section) induces considerable magnetic polarity or remanence in the specimen. The material becomes lodestone. A powerful electro-magnet is much more efficient.”
“Perhaps the majority of the mineralogists of the future will be ‘synthesizers’ able to make from a few simple raw materials ‘pure’ minerals for applied science and industry. Conspicuous recent examples are quartz and diamond. Does this call for a redefinition of the scope of mineralogy? If one applied 150,000 bars of pressure to make stishovite, has he become a physicist, or is he still a mineralogist? If he uses physical or chemical theory to interpret some natural occurrences or their absence should he be called a geophysicist or a geochemist rather than a mineralogist?”
Due to Bruno Doss’ 1906 work on three gas wells on the property of the Mel’nikov brothers in the Samara Province of Russia, between 1912 and 1964 the black iron sulfide mineralogists now know as greigite was known as melnikovite. See The Oxidation and Reduction Potential in Geology, Consultants Bureau, New York (1972) (trans. J. Paul Fitzsimmons) (“O-R”) citing, among other papers, Doss’ Ezhegodnik po Geol. I Mineralogii Rossii, Vol. 12, No. 5-6 (1911).
Henry Lepp apparently was the first person to synthesize melnikovite. Economic Geology, Vol. 52, pp. 528-535 (1957). Lepp did his melnikovite synthesis and wrote his report on melnikovite’s “probable geological significance” as part of his 1954 University of Minnesota doctoral dissertation under the guidance of Dr. Gruner. Id. at 534.
Based on R. A. Berner’s work, as reported in American Mineralogist, Vol. 49, pp. 543-555 (1964) and in O-R, it was only Lepp's lack of “natural” melnikovite specimens that prevented him from providing "positive proof” of correspondence between natural and synthetic melnikovite. See Economic Geology, Vol. 52 at pp. 528-529. Note too that O-R’s author, Mikhail F. Stashchuk, was the director of the Laboratory of Mineral Forming Processes of the Institute of Mineral Resources of the Ukranian Ministry of Geology when he publicly stated that before the appearance of the structural investigations of Lepp it was impossible to state reliably what melnikovite was. O-R, p. 68.
Dr. Gruner noted his hand-specimen of lodestone showed greater magnetism at the edge than at the center and it is on the surface, at the extremities of magnetite deposits, where lodestone is found. Lepp observed different phases of Fe2O3.H2O when his synthetic "melnikovite" oxidized in water as opposed to room-temperature drying. See Economic Geology, Vols. 24 and 52, infra. These observations, and the observation of how use of a firm cavity can counteract the magnetic edge effect and avoid shear, may prove meaningful as research continues on...
LODESTONE FROM GREIGITE (too right!)
Scientific Papers of note (in addition to those cited above)
American Mineralogist, Vol. 79, pp. 654-667 (1994)
Geophysical Research Letters, Vol. 26, No. 15, pp. 2275- 2278 (1999)
Geophysical Journal International, Vol. 141, pp. 809–819 (2000)
American Mineralogist, Vol. 91, pp. 1216-1229 (2006)
Rev. Geophys., Vol. 49, Issue 1 (2011)
Science, 334:6063, pp. 1720-1723 (2011); https://m.youtube.com/watch?v=LeKx6jrDOos, accessed March 6, 2016
Geochem. Geophys. Geosyst., 14, 5430-5441 (2013)
J. Mater.Chem.A 2, pp. 1903-1913 (2014)
Earth-Science Reviews, Vol. 151, pp. 1-47 (2015)
Environmental Microbiology Reports, 8: 1003–1015 (2016)
"lodestone from greigite" research made possible by
and the libraries of Occidental College and Caltech
-- Gail Clement of Caltech, for her encouraging words and
help accessing O-R and J. Mater.Chem. A 2
-- Dr. Scott Fendorf for helping our daughter in her
Stanford University geology/soil science studies and for
his recent reference to Cornell and Schwertmann's book
The Iron Oxides, WILEY-VCH (2d ed., 2003). The graph on
page 160 (Fig. 7.21) showing normalized remanent
magnetization as a function of temperature for maghemite,
greigite, magnetite etc. proved illuminating for many reasons.