GeoLog

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Imaggeo On Monday: Quartz – sericite mylonite, Calamita, Elba

Imaggeo On Monday: Quartz – sericite mylonite, Calamita, Elba

Concomitant thrusting and magmatism resulted in the development of ductile mylonites in the Calamita Schists, part of the contact aureole of the Late Miocene Porto Azzurro pluton. This mylonite is made up of stretched and recrystallized quartz layers, interlayered with thin sericite-rich levels. Sericite resulted from the crushing of contact-metamorphic minerals such as andalusite, cordierite, and ...[Read More]

Imaggeo On Monday: Geometric Microscape of Agate

Imaggeo On Monday: Geometric Microscape of Agate

“Crazy Lace” is an agate collected in Mexico, which offers great opportunities for aesthetic photomicrography. Here we see the common arrangement of fibers of chalcedony (microcrystalline quartz) in parallel bands alternating with black thin layers of Fe oxides. Polarized light photomicrograph, crossed polarizers and red tint plate. width 5.4 mm. Sample kindly provided by Denise M. Har ...[Read More]

Imaggeo On Monday: Blue Olivine in an unusual basalt

Imaggeo On Monday: Blue Olivine in an unusual basalt

Blue Olivine set in a matrix of pyroxene, magnetite and plagioclase in a basalt collected by the photographer, Bernardo Cesare, on the shore of the Sea of Galilee, Israel. Polarized light photomicrograph. Crossed polarizers and red tint plate. Width c. 2.7 mm. Who may have been throwing this stone a couple millennia ago?   Description by Bernardo Cesare, after the description on imaggeo.egu.e ...[Read More]

Colour deficient vision and the geosciences; just another way of looking at things

Colour deficient vision and the geosciences; just another way of looking at things

Like a reasonably large proportion of the population, I have colour vision deficiency (also known as colour deficient vision or colourblindness). I’m not going to get into the technical aspects of what this is like as they are covered well here and here, and you can do an Ishihara test, and other tests here, to check your own vision. The other reason I’m not going to discuss the technicalities of ...[Read More]