Electron-microprobe analyses of chromite and olivine from alpine ultramafic complexes
No abstract available.
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Geology topics
M. L. Bird
Publications and source records attributed to M. L. Bird.
Compositional variations in wolframite from the Hamme (Tungsten Queen) mine, North Carolina
A microprobe study of wolframite from the Tungsten Queen mine, Hamme district, North Carolina, proves it to be almost pure huebnerite. Concentric zoning, which shows up as light-brown and dark-brown bands, indicates small variations in the content of FeO. There is no apparent correlation between the small variations in the composition of the wolframite and its position in the mine. The Fe/Mn ratio of the wolframite is not indicative of the temperature of crystallization.
North Carolina↗
Microprobe study of olivine chromitites of the Goodnews Bay ultramafic complex, Alaska, and the occurrence of platinum
Electron-microprobe analyses of the dunite and olivine chromitite of the ultramaflc complex at Goodnews Bay, Alaska, show that the chromite contains more ferrous and ferric iron than is found in chromite from alpine or stratiform complexes. The iron-magnesium distribution coefficients between chromite and olivine demonstrate that more ferrous iron is partitioned to the chromite in the Goodnews Bay complex than to the chromite in stratiform chromitite but that the distribution is similar to that for alpine chromitite. The high iron content of the chromite and olivine at Goodnews Bay and the general geology of the complex indicate that it is a concentric-type ultramaflc complex similar to the platinum-bearing concentric complexes of southeastern Alaska. A platinum-alloy inclusion in the chromite found in the ultramaflc section at Goodnews Bay demonstrates that the olivine chromitite is the source of at least some of the platinum.
Alaska↗
Lunar soil: Size distribution and mineralogical constituents
The lunar soil collected by Apollo 11 consists primarily of submillimeter material and is finer in grain size than soil previously recorded photographically by Surveyor experiments. The main constituents are fine-grained to glassy rocks of basaltic affinity and coherent breccia of undetermined origin. Dark glass, containing abundant nickel-iron spheres, coats many rocks, mineral, and breccia fragments. Several types of homogeneous glass occur as fragments and spheres. Colorless spheres, probably an exotic component, are abundant in the fraction finer than 20 microns.
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