iPhone Petrography

Here’s my attempt at photographing the metamorphic thin sections we are analyzing in petrology. All the pictures were taken on my iPhone and as such the resolution isn’t all that great, but you can still get a feel for the texture and mineral characteristics. Taking these pictures was an exercise in patience as it required a very steady hand. As soon as the picture showed up I started taking as many pictures as possible to increase the chance at getting a  good one. So, there are three sets of pictures, two to each set. The first picture in each set is of the thin section in plane transmitted light. As to be expected, not much can been seen except for garnets, the outlines of some biotites and what I’m thinking is an amphibole that’s seen better days. The second set of pictures is the same image, but in crossed polar light.

Set One: garnet, biotite and quartz

Garnet and some biotite in plain light

Same garnet, but in crossed polar light

Same garnet, but in crossed polar light

Set 2: What I’m thinking is amphibole. the 120 degree cleavage isn’t readily apparent, but I’m finding metamorphic thin sections don’t necessarily reveal all their secrets easily

The darker mineral- possible amphibole?

Same image in cross polars

Set 3: Quartz and biotite. The first picture isn’t the greatest because I had a hard time controlling the glare at the bottom.

Not much to see except for the brown biotites

A much cooler picture than it's plane light cousin

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2 thoughts on “iPhone Petrography

  1. Yep, definitely hornblende in the middle one. The green grain shows the typical cleavage.

    What’s the high-relief phase in the bottom photo? Looks like something that could be important for understanding the grade.

    • To be honest, I’m not sure what that phase is. I didn’t get to spend much time on that thin section, but I noticed a lot of sheared and stretched quartz. Interestingly enough, there was also what looked like bands of garnet, similar to the quartz. It displayed all the optical characteristics of garnet except for the euhedral shape and didn’t have a poikilitic texture. I should know more when I go back to lab on Tuesday.

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