Sunday, January 18, 2009

Scanning your samples

Ever wondered how to document your samples and thin sections but didn't feel like spending hours taking fotos? Scan them! It works nicely with any kind of more or less planar surface. No need to grind or polish your sample. Just try to get a somewhat flat surface. In my mapping area one may find palaeokarst cavities in Jurassic limestones infilled with worthless (too small, Fe-concentration too low, too much cover and largely eroded) Eocene bean ore cemented by orange-brown carbonate. I used one to test the method and it works! Below you can see a scanned piece of bean ore.

Diameter roughly 3 to 4 cm.
Click to enlarge!

You can get good results for scanning samples with 600 dpi, however, 1200 will provide a clearer and bigger image and will generally be enough for any kind of sample. The above image has a resolution of 1200 dpi. If you want to scan thin sections 2400 dpi or more are recommendable. Unless you want do use the images only for illustrating the process of manufacture. My scanner can go up to 7200 dpi which delivers fantastic scans with great detail - if my computer doesn't crash under the load of truly huge images. So keep in mind to have a strong computer power behind your scanner.

That's it already! Scanning itself is done the same as for any other material. Take caution not to drop your samples into the scanner or scratch the plastic surfaces.


ReBecca Foster said...

I have done this before also. I put down an overhead sheet to help protect the scanner glass from grit and scratches :)

Lost Geologist said...

Very good idea. I didn't think about that, yet. Thanks for letting me know!

You don't happen to have posted about it on your blog? Else I could place a reference to the post.

BrianR said...

This is a good idea ... very simple and easy, just the way I like it!

ReBecca Foster said...

Nope, I never thought about putting a post together on it.

Silver Fox said...

A great idea! Thanks for posting about it.

Ron Schott said...

It is a great idea. You should drop a ruler on there along with your sample for scale so as to improve the scientific value of your samples.

R Hofmann said...

Just if you have polished slabs....I got even better results with water:

Take an overhead sheet, tape it with some plastic foil that the construction entirely covers the scanner. Apply some water to the overhead sheet and place the slab on it. Make sure that there is no air between the foil and the sample.

Oh, it works with polished slabs and thin sections only.

Lost Geologist said...

Thanks for all your comments! It's a great addition! I later realised I should have put a ruler or something similiar for scale onto it. I think I have an overhead sheet somewhere with 1cm square boxes on it. That would work, too. In a lot of cases wet samples will improve the scan, not just in polished sections. But it depends a little on the kind of rock I noticed. For example I makes hardly a difference with my already very bright limestones.

andrew said...

Before I got my first digital camera, I built a large part of my minerals gallery with the scanner. Some are still there, most notably my diamond specimen, scanned at 1200 dpi.