Double refractive minerals in single refractive hosts.

[Tim S]

Hi y'all,

for my work I get to peer through microscopes. Catching the images I see has become a hobby, and as you guys can probably imagine, even an obsession. I was pointed to this forum by a mutual friend: G4lab, who taught me about microscopes & microphotography.

I shoot through a Wild M400 and have an Oly E-510 screwed onto it. Here's a few shots of DR inclusions in SR minerals in between crossed polars; always good for colorful shots:


DR crystal inclusion in a spessartite.


DR crystal inclusion in a spinel.


DR crystal inclusion in another spinel.

No stacking & no photoshopping apart from cropping & resizing.

It's no bugs... but... it's microphotography
I hope you guys enjoy 'm,

best twitches

Tim Spauwen

[Charles Krebs]

Tim,

Welcome!

I like these images. Very graphic. You obviously know exactly what we're looking at... but to my uninformed eye, they all look a little "celestial". And at the same time (even though I know we're looking at minerals) the lower two also have a certain "biological" look to them.

[g4lab]

[bertrand_amici]

Hi Tim,
I certainly enjoied your beautiful pictures! Do you have an idea what these birefringent minerals inside the isotropic spessartine and in the spinels might be? Are these natural minerals?

Cheers, Thomas

[Tim S]

Charles, thanks for the welcome!

Thomas, they are definitely natural minerals but their ID... no idea really... Because they show iridescent colors between x-ed polars we can tell it's double refractive minerals. Light is slowed down and split into two polarized planes when it enters a DR mineral. These two planes enjoy different 'resistance' and consequently one ray is slowed down more than the other. This causes the slower ray to lag behind the the faster one so that when the light leaves the DR mineral the faster one is already out when the slower one still has to leave the material. This phenomenon is called retardation and its magnitude is depending on the birefringence of the material and the distance light has to travel through the material. Because of this retardation interference of certain wavelengths (colors) can occur upon the light exiting the DR material which results in color perception on our side. Because of the differences in thickness of those inclusions (thicker in the center and thinner at the edges) different amounts of retardation occur. These different amounts of retardation cause different wavelengths to suffer interference which results in all these different colors that make these inclusions so photogenic.

Single refractive minerals don't split the light into two different planes so there is no retardation to cause interference (read: the result of interference: color).

all the best,

Tim

[Aynia]

Beautiful and arty.

Not everything here is about bugs... it might appear to be, but we all enjoy and appreciate anything small and tiny and unseen etc.