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Laughon, R. B.

Publications and source records attributed to Laughon, R. B..

Morphology and composition of chalcopyrite, chromite, Cu, Ni-Fe, pentlandite, and troilite in vugs of 76015 and 76215

Vugs from 76015 and 76215 are lined with euhedral crystals of plagioclase, pyroxene, ilmenite, Ni-Fe, and troilite. Smaller crystals of chromite, pentlandite, and chalcopyrite occur on the surface of the troilite in 76015. Wire Cu and dendritic-metallic Cu occurs with metallic Ni-Fe and troilite in some vugs of 76215. Troilite in both samples may have crystallized from an immiscible sulfide liquid. With falling temperature, chalcopyrite, and pentlandite may have exsolved from the troilite in 76015. By contrast, metallic Cu may have formed in 76215 by thermal breakdown of a bornite, troilite, and Ni-Fe assemblage which originally crystallized from a low-Ni immiscible sulfide liquid.

Carter, J. L.

Vapor-phase crystallization of iron in lunar breccias

A vuggy breccia fragment from sample 67482 contains an iron crystal with a previously unreported crystal form, the trigonal trisoctahedron. The dominant habit is the trapezohedron with smaller cube and trisoctahedron faces. The geometric relationship of the iron crystal to the plagioclase-pyroxene substrate indicates that the iron crystal was the last mineral to form in the vug. The open network of plagioclase and pyroxene crystals lining the vug wall and the iron crystals with well-developed crystal faces suggests growth from a vapor phase.-

Clanton, U. S.

Iron crystals in lunar breccias

Many of the vugs in the highly recrystallized breccias from Apollos 14, 15, and 16 contain euhedral iron crystals. Three populations have been recognized based on crystal habit. In the first group the trapezohedron predominates and the cube faces are smaller. The second group is characterized by the cube as the dominant form; trapezohedron and tetrahexahedron faces are smaller and about equally developed. The dominant habit of the third group is the octahedron with smaller but equally developed cube and dodecahedron faces. Iron has been mobilized and redistributed in a vapor phase. The euhedral crystals, the abundant growth steps, and the open network of substrate crystals clearly support the concept of growth from a vapor-phase.

Clanton, U. S.

New data on guildite

X ray powder and chemical data on monoclinic secondary mineral guildite from mine fire at Jerome site

Laughon, R. B.