Crocoite

Geopressure · Post by **Geopressure** » Sun Apr 21, 2019 3:47 pm

Crocoite from Tasmania

Stacked at 6.75X
Field of View 3.2 mm

Editing this one nearly wore me out and still not done...

JL · Post by JL » Mon Apr 22, 2019 6:32 am

It might been not finished yet, but going pretty nicely.

Great picture.

Sumguy01 · Post by **Sumguy01** » Mon Apr 22, 2019 8:22 pm

Looks great to me.
Thanks for sharing.

BugEZ · Post by **BugEZ** » Sat Apr 27, 2019 11:22 am

Very nice photo!

Lou Jost · Post by **Lou Jost** » Sat Apr 27, 2019 12:37 pm

Very nice. It might be interesting to reduce the glare slightly, by cross-polarization, if you aren't already doing that. Then the colors would be more intense.

Geopressure · Post by **Geopressure** » Sat Apr 27, 2019 2:22 pm

Thanks to all for the feedback!

Lou: I agree the reflections are a bit stronger than desired. It is ironic, since reflections are often part of what makes larger mineral specimens attractive when examined by eye and moved around in the hand. I have never tried using polarizing filters though I've wondered about it. They might interact with minerals in undesirable ways at times but I don't even know what gear should be used to best accomplish this.

This stack is also plagued with a widespread orange halo-tint which should probably be further edited.

Len Willan · Post by **Len Willan** » Sat Apr 27, 2019 3:10 pm

Your photograph shows great skill and interest in the subject

Here is the current history of one the crocoite mines.

The Dundas Extended Mine has been mined by Mike and Eleanor Phelan since the mid-1980s — but its origins date back to 1892, when it was used as a prospecting tunnel to look for silver lead.
The couple has been mining the crystal formations known as crocoite from the hobby mine.
Crocoite is the mineral emblem of Tasmania — and the Dundas area is one of a handful of places in the world where it is found.
• The hobby mine on Tasmania's west coast is for sale for $300,000
• The owners have been mining a crystal formation known as crocoite and selling it to local shops
• The mine includes a rail cart, camp facilities and even a barbeque
For $300,000, you could own a hobby mine in a Tasmanian ghost town
https://www.abc.net.au/news/2019-04-26/ ... e/11047052

Lou Jost · Post by **Lou Jost** » Sat Apr 27, 2019 3:52 pm

Geopressure, yes, the reflections are important, and I don't think they should be removed completely, but they obscure the color of the crystals. Read up on cross-polarization to get the details, but the technique involves putting a polarizer over your light sources, so all the light is polarized. Then put another polarizer on your lens (or between the objective and tube lens) and rotating that polarizer until you get the effect you want. The reflections will disappear when the polarizer is in the correct position, and will appear strongly when the polarizer is rotated 90 degrees from that position.

Here's an example I posted using a shiny seedpod as a subject. In this case I did not want to eliminate the reflections entirely, but just reduce them:

http://www.photomacrography.net/forum/v ... 362cf8afc9

You need to use good polarizers, otherwise instead of disappearing the reflections turn purple from leaking purple light.

Geopressure · Post by **Geopressure** » Sun Apr 28, 2019 10:04 am

That seedpod example is impressive. There are a number of colorful yet highly reflective minerals that are problematical and might benefit from this approach. Thanks for sharing Lou!

Brad

Lou Jost · Post by **Lou Jost** » Sun Apr 28, 2019 10:29 am

I highly recommend the method. You can keep as much or as little of the reflections as you want, by adjusting the polarizer.

Smokedaddy · Post by **Smokedaddy** » Sun Apr 28, 2019 11:36 am

Very nice.