The distribution of alpha-radioactivity in the vicinity of uranium and of certain variant radioactive halos in biotite was investigated by the fossil alpharecoil method. Within the limits of the method I could not confirm a previously proposed hydrothermal mechanism for the origin of certain variant halo types due to polonium isotopes.

Compositions of biotite from three different rock types of Mashhad granitoids, i.e., granodiorite, monzogranite and leucogranite in NE of Iran have been documented by electron microprobe and wet chemistry for Fe3+ and Fe2+. Mashhad granitoids have been geochronologically and petrologically grouped into G1 and G2 phases. Microprobe data show that the total Fe contents in biotite from G2 leucogra...

Etched track opening geometries in Biotite, Phlogopite and soda-lime glass irradiated with swift heavy ions [197Au(11.64 MeV/n), 136Xe(11.56 MeV/n), 58Ni(11.56 MeV/n)] at different angle of incidence have been studied using appropriate chemical etching technique. Different geometries (Hexagonal, irregular polygon, triangular in case of Biotite and Phlogopite, and circular & elliptical in case o...

At the first site, the Weinsberg (Moldanubian) granite and an older quartzmonzonite facies of the South Bohemian pluton in Austria both contain orthopyroxene and clinopyroxene and must have crystallized from magmas at high temperatures. The granite contains orthoclase megacrysts (as much as 10 to 20 cm long), which (1) are chemically zoned with Ba-rich cores (1 to 2 % mol Cs; and locally as muc...

Semi-pelitic rocks ranging in grade from the prehnite–pumpellyite to the greenschist facies from southeastern Otago, New Zealand, have been investigated in order to evaluate the reactions leading to formation and breakdown of stilpnomelane. Detrital grains of mica and chlorite along with fine-grained authigenic illite and chlorite occur in lower-grade rocks with compactional fabric parallel to ...

It typically occurs as an alteration product at the contact between felsic and mafic or ultramafic rocks such as pyroxenites and dunites. It also occurs in carbonatites and metamorphosed magenesium rich limestone. Associated mineral phases include: corundum, apatite, serpentine and talc. It occurs interlayered with chlorite, biotite and phlogopite.[2] Vermiculite Wikipedia, the free encyclopedi...

the relations of fibrolite-biotite are discussed by presenting data from the ardara aureole, nw ireland. biotite-fibrolite intergrowths are developed in all three aureole zones including: the outer kyanite-bearing andalusite zone, the middle kyanite-free andalusite zone and the inner prismatic sillimanite zone. a strain-assisted mechanism is proposed for the fibrolitisation of biotite in the ar...