Sand Grains

[geo_man]

Inspired by heyitsmedusty's post on photographing micrometeorites, and while waiting for my magnet to arrive in the mail, I shot a few quartz sand grains from the beach (4 in polarized light) to practice my stacking skills. I know I will have more trouble with micrometeorites as they will be opaque. Imaging sand grains w 10x and 25x objectives is quite easy, interesting and is a good project to do with young folk. Cheers!

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sand1.jpeg (122 KiB) Viewed 2675 times

[DonSchaeffer]

It is a good project! It's a way of looking at the world. You should do a lot more like this.

[Phill Brown]

Salt grains also.

[KurtM]

Nice pix. What beach is this from?

[ADi]

very nice !

[geo_man]

Thanks guys. And Kurt, location is south shore Long Island NY, reworked glacial deposits. Here is pic; clear is quartz, pink is garnet, black are iron/metal oxides. Cheers!

LI beach sand.jpeg (334.58 KiB) Viewed 2556 times

[KurtM]

Thanks for that. As a bit of an arenophile, having a location and any other context is what makes such images as yours truly interesting (and they are, too - nicely done!). Seeing a thread titled 'Sand Grains' gets me stoked, and I hope others might be inspired to do just what you did with samples taken from their part of the world.

[woyjwjl]

Okay, I'll put a terrible picture here

P1020639.jpg (53.96 KiB) Viewed 2490 times

This is a diamond abrasive (6.5 microns), and for this semi transparent material with single refraction, an electron scanning microscope should be the only choice.

[Andy Resnick]

I shot a few quartz sand grains from the beach (4 in polarized light) to practice my stacking skills.

Those look amazing- cheers!

[geo_man]

thanks again everyone. here are my last pics from this shoot (step away from the microscope!), its interesting how the details change with the different lighting. You can see more detail without polarization. And you add some interesting color/texture with some side light from a halogen illuminator. Cheers!

25x no pol.jpeg (184.62 KiB) Viewed 2439 times

25x pol.jpeg (229.06 KiB) Viewed 2439 times

10x pol.jpeg (139.81 KiB) Viewed 2439 times

10x pol plus side light.jpeg (161.87 KiB) Viewed 2439 times

[heyitsmedusty]

Wow, your photos are looking great! You are doing an excellent job using your light/shadow to capture textures, similar to what you will be seeing in micrometeorites.

If you ever need any help with micrometeorite stuff (finding/photographing/identifying) just reach out! I love this stuff and it’s awesome when more people get into it.

Cheers!

[DonSchaeffer]

What do the colors in a polarized image really mean? I've never seen an interpretation.

[Phill Brown]

The light is refracted in the silica in the same way as a prism of clear glass.
Polarising helps with clarity, rainbow pictures are much more colourful with a polariser,rotate until the colours are strongest.

[Sure Squintsalot]

Thanks guys. And Kurt, location is south shore Long Island NY, reworked glacial deposits. Here is pic; clear is quartz, pink is garnet, black are iron/metal oxides. Cheers!

I've run into windblown deposits of of nearly 100% garnet sand at Captree on those windy winter days. This garnet sand layer runs in narrow streaks and is paper thin and colors the sand a light purple. I'm not really sure why the garnet remains as a surface layer, but the heavier oxides are absent.

Perhaps you can distinguish the differences in those grain surfaces between saltation and the hammering these grains get at the surf line?

[geo_man]

What do the colors in a polarized image really mean? I've never seen an interpretation.

Don, do a bit of research on mineral birefringence. e.g., https://sites.und.edu/dexter.perkins/op ... ngence.htm

Thanks guys. And Kurt, location is south shore Long Island NY, reworked glacial deposits. Here is pic; clear is quartz, pink is garnet, black are iron/metal oxides. Cheers!

I've run into windblown deposits of of nearly 100% garnet sand at Captree on those windy winter days. This garnet sand layer runs in narrow streaks and is paper thin and colors the sand a light purple. I'm not really sure why the garnet remains as a surface layer, but the heavier oxides are absent.

Perhaps you can distinguish the differences in those grain surfaces between saltation and the hammering these grains get at the surf line?

Sure Squintsalot: there is a long history of attempting to determine sand grain depositional history by analyzing surface texture imaged with SEM, e.g.,
https://gq.pgi.gov.pl/article/view/8786/pdf_819
https://www.kau.edu.sa/Files/320/Resear ... _33633.pdf

Thanks for commenting!