One woman's quest for geological understanding!

Petrology & MicroscopeCategory Archives

Foraminifera under the microscope – A learning experience

Tweet  Today has been a day for joyful microscope experimentation! I recently received a Thin Section (TS) / Slide of Holocene Foraminifera from the Philippines (3357 feet).  Not my area of expertise at all, but very pretty.  And after years of seeing studies where foraminifera were used as proxies for climate change in geological history, and spending so much time incorporating these into my project course and personal research, it seemed a great idea to actually look at some under… Continue reading »

Photography down the microscope…

Soooo I started taking excellent photos…. and was about to label and upload photos and films I took through my polarizing microscope, when I realised I needed scale!  Rule #1!

So, I gave up on the maths – the slight zoom in my camera ruled out that – and invested in an “Advanced Calibration Slide”, which arrived yesterday.

Calibration Slide

It has five calibration patterns.

0.07mm, 0.15mm, 0.6mm and 1.5mm calibration dots.

X-Y Calibration ScaleX-Y calibration scale (In the circle in the picture of the slide above) with a smaller division of 0.01mm. The scale is 1mm long in both X and Y direction and is first divided into 0.1mm and them 0.01mm. At the centre, it has a 0.04mm square divided by 5 lines in both X and Y direction and providing much more choice for calibration.

Now let the fun begin on a large small scale!

My Microscope

I have been meaning to post this for some time, but this time last year, my family clubbed together to purchase this amazing microscope for me!


It is a polarising microscope with transmitted illumination, binocular viewing head, phototube and strain free infinity corrected flat field objectives.

This, and the 2013 Christmas gift of a Canon EOS600D from my brother (John) and his wife, have put me in a great position to enjoy geoscience in greater detail!

Getting to grips with the set up, settings and ins and outs of this new equipment (especially the new camera!) has taken some time, but I hope to document it all soon!

Given sufficient free time, I will be posting Thin Section videos / photos more frequently in my blog!

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Baryte in Thin Section

This is a thin section of  radial growths of Baryte (or Heavy Spar).

This slide shows plumose (literally like feathers) interference structure.

In thin-section it is similar to other sulphates but can be distinguished by its straight extinction, moderately high relief, small 2V and paragenesis.

  • Crystals are often intergrown, rosettes, as demonstrated in this TS.
  • Four cleavage directions.
  • Interference colors rangeup to first-order yellow.
  • Sometimes pale colors-brown in PPL with weak pleochroism.

Collected from a mineral vein in the Hope Valley, near Castleton, Derbyshire.


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