Materials survey, iron ore.

Mode of access: Internet.

In the matter of United Steelworkers of America-CIO and various steel and iron ore companies : case no. D-18-C.

"New York, N.Y. February 13, 1952"--V. 3.

A study of minimum rate and increment differentials in steelworker-organized plants of companies, in the basic steel, pig iron, and iron ore industries, and in other major companies with 2,500 or more employees in steelworker-organized units in the United States and Canada for the three contract years 1956, 1957, 1958, showing A. remaining differentials, B. reductions in and elimination of differentials, C. increases in differentials.

Mode of access: Internet.

In the matter of United Steelworkers of America-CIO and various steel and iron ore companies : case no. D-18-C, appendix to a guaranteed wage plan for the workers in the steel industry /

"Union exhibit no. 11A"--Cover.

A. Geology and mineral paragenesis of the Pea Ridge Iron Ore Mine, Washington County, Missouri : origin of the rare-earth-element- and goldbearing breccia pipes /

Includes bibliographical references.

Parallel photographs of the spectra of the sun, of iron, and of iridium, from the line (H) to near the line (D), in six sections. Also separate photographs of the spectrum of titanic iron ore, in six sections.

Half-title. Reprinted from the Monthly notices of the Royal astronomical society, vol.XLIX, no.7.

Dating paleochannel iron ore by (U-Th)/He analysis of supergene goethite, Hamersley province, Australia

(U-Th)/He dating of late-stage authigenic goethite, combined with corrections for diffusive loss of He-4 by the He-4/He-3 methodology, reveals strong correlation between a sample's age and its depth in ferruginized channel sediments from the Yandicoogina deposit, Western Australia. Corrected ages, ranging from ca. 18 Ma near the surface to ca. 5 Ma at the bottom of the profile, indicate that ferruginization of the aggraded channels becomes progressively younger with depth. This trend is consistent with goethite precipitation at the groundwater-atmosphere interface during water table drawdown driven by the aridification of Western Australia during the Neogene. The results demonstrate that the (U-Th)/He system is ideal for dating goethite if diffusive loss corrections are applied. The approach is suitable for dating weathering reactions on Earth and should also be suitable for dating Fe oxyhydroxides in the Martian regolith.

40Ar/39Ar dating of Mn-iron ore of the Sapecado Mine, Qadrilatero Ferrifero, Brazil

The SW region of Amazonian craton presents policyclic evolution between 1.80-1.00 Ga and is comprised of the Rio Negro-Juruena, Rondoniana and Sunsas Provinces. The evolution of this region has being characterized by four orogens: Alto Jauru (1.79-1.74 Ga), Cachoeirinha (1.58-1.52 Ga), Suíte Santa Helena (1.45-1.42 Ga) e Sunsas/Aguapeí (1.0-0.9 Ga). The Alto Jauru orogen consists of TTG gneissic associations, greenstone sequences and intrusive granitoids origined in volcanic arc setting. Eight 40Ar/39Ar step-heating analyses were carried out in minerals (biotiteand hornblende) to investigate the thermal history and crustal evolution of this region. From the Alto Jauru orogen was sampled the gneiss banded and two biotite grains provide large dispersion of apparent ages, suggesting heterogenity in reservoir of the argon. Apparent age diagram yielded integrated ages of 1472 ± 6 Ma, interpreted as minimum ages of regional cooling episode. Three analyses of hornblende present ages varing from 1310 to 1400 Ma, possibly because smaller grain size become more susceptible to argon loss. 40Ar/39Ar step-heating methodology applied on biotite of pyroclastic tuff (U-Pb age about 1758 ± 7 Ma) presented integrated age of 1507 ± 7 Ma. The results found for this terrane demonstrated a geochronological correlation with metamorphic process linked Cachoeirinha orogen. Biotite and hornblende grains separates from granite and a tonalite origined during Cachoeirinha orogen were analyzed and the apparent age diagrams indicated well-defined plateau ages of 1520-1540 Ma. Biotite grains from a granitic sample were analized, and integrated ages about 1526 ± 2 Ma were obtained due argon loss in the initial steps. Thermochronologic history of SW region Amazonian craton is coherent with regional policyclic events and 40Ar/39Ar ages here presented probably correspond to regional cooling period of Cachoeirinha orogen.