Mineral grains

Here you can discuss DIY adaptations to the microscope.
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Glot
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Mineral grains

#1 Post by Glot » Wed Jul 07, 2021 8:12 am

There is a DIY tutorial online for a technique involving glueing a crystal grain to a needle and rotating it under polarised light. Does anyone know what this technique is called or even better, the tutorial I am looking for?

Greg Howald
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Re: Mineral grains

#2 Post by Greg Howald » Wed Jul 07, 2021 12:43 pm

Haven't seen that tutorial but have seen several others concerning the use of petrographic microscopy, have a petrographic scope and have studied. Rotating a mineral grain or thin section under extinct polarized light and using certain filters is the major means of mineral identification. Look on YouTube. Subject is " Optical Mineralogy. "
Enjoy. Greg

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patta
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Re: Mineral grains

#3 Post by patta » Wed Jul 07, 2021 1:45 pm

The rotating needle, may be called the "spindle stage".

Glot
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Re: Mineral grains

#4 Post by Glot » Sat Jul 10, 2021 8:08 am

Thanks Patta. Thats what I was trying to recall.
For those unfamiliar, this system help. Someone shows how to make a home made one.

https://youtu.be/j955_cOi_qE

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patta
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Re: Mineral grains

#5 Post by patta » Sun Jul 18, 2021 11:15 am

An extremely crude but effective implementation, to hold and rotate insects:
https://www.photomacrography.net/forum ... =43787

Hobbyst46
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Re: Mineral grains

#6 Post by Hobbyst46 » Sun Jul 18, 2021 1:18 pm

Decades ago, gluing a crystal to a rotating needle, such that its orientation in space was reproducible and defined along one of the crystal axes, was a standard technique of crystallography. The needle was mounted with plasticine (or similar stuff) to a simple goniometer head. Crystals were glued with shellac for example. Such operation was best done under viewing with a stereoscope (say, 0.7X-1X).

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