occur in amygdules by itself, as needles in quartz, or associated with chlorite or epidote, from which it is not easily distinguished. Much of the pumpellyite is bluish-green in contrast to the epidote, which is yellow-green. Its most common occurrence is as a replacement of rock in flow tops, yielding a hard, dense, greenish-gray to
Isle Royale Mine (241 E 2057) containing amygdules of pumpel-Iyite. The rock was coarsely crushed, the powder washed in water, and after a brief time the finest powder decanted while still suspended and allowed to settle very slowly. This was found to consist essentially of pumpellyite but with a slight impurity of
Michigan pumpellyite - Mineralogical Society of America
Pumpellyite appears at two periods in the complex paragenesis of the amygdaloids. It is one of the late magmatic (pneumotectic) minerals, formed before the copper began to be deposited and before the invasion of the formation by the ore-bearing solutions.
Amygdaloidal Minerals - Michigan Technological University
The brightly colored minerals of the zeolite and prehnite-pumpellyite facies fill the vesicles of the Keweenawan lava flows. In many of these photos I used the expertise and great collection from the AE Seaman Mineralogical museum , foremost mineral museum in the midwest, and George Robinson, Bob Barron and John Jaszczak helped select samples ...
Prehnite and pumpellyite are closely associated with chlorite, calcite and quartz, and they mainly occur in white colored veins or in amygdules in metabasites of the relevant area, but actinolite and epidote are rare in them. Pumpellyite is characterized by iron-rich composition (7.2-20.0 wt% as total iron as FeO) and its range almost
Pumpellyite - Wikipedia
Pumpellyite occurs as amygdaloidal and fracture fillings in basaltic and gabbroic rocks in metamorphic terranes. It is an indicator mineral of the prehnite-pumpellyite metamorphic facies. It is associated with chlorite, epidote, quartz, calcite and prehnite.
Chlorastrolite - Photo Gallery - mindat.org
Chlorastrolite is Michigan's official state gemstone and is known locally as "Isle Royale Greenstone". Scientifically, they are a form of the mineral pumpellyite. Available analyses suggest the Michigan pumpellyites are magnesium-dominant, intermediate solid solution series between pumpellyite (Mg+), pumpellyite (Fe2+) and pumpellyite (Fe3+).
Pumpellyite from zeolite facies metabasites of the Horokanai …
Pumpellyite occures in zeolite facies metabasites of the Horokanai ophiolite in the Kamuikotan zone, Hokkaido, Japan, filling veins or amygdules, replacing igneous plagioclase or clinopyroxene or olivine, and occupying the matrix.
In most cases, pumpellyite replaces Plagioclase phenocrysts and microlites, and also occurs as aggregates together with albite-filling amygdules and pores of the rock fragments. It occurs rarely in the matrix of the rock as disseminated crystals. Strong pleochroism is observed in pumpellyite replacing Plagioclase (X' = yellow and Z' = colorless).
(PDF) Prehnite and Pumpellyite in the Archaean Sitagota
2008年8月1日 · Pumpellyite occurs as fibrous aggregates, lining or filling amygdules, whereas prehnite occurs sporadically in amygdules as clusters of tiny prismatic crystals. Pumpellyite is iron-rich,...