FMF - Friends of Minerals Forum, discussion and message board

[cornz]

Ok, a good friend has asked me if I know what these are. I have no idea and wondered if anyone here had any clue.

Here is a bit of background from him:

This was found in 2010 whilst I was working in the Sistani desert near Marjah, Helmand Province, Afghanistan.

I noticed an odd depression on the desert floor and thought at first it was a trapdoor spider hole or that something had hit the sand hard causing the hole in the sand to be a funnel shape.
Using a wooden probe, I checked gently around the hole and approximately 10 inches below the surface I found this object and nothing else. It is un-reactive to magnets, so I guess it has no ferrous metal content, it weighs approx. 10.5 ounces.

[Peter Megaw]

We need a little more information than "non magnetic" ...especially hardness...I doubt you can scratch this with a pin or tip of a knife, but that would be the first test I'd recommend

That said, this looks like a chert nodule that has been weathered out of limestone and sandblasted by desert winds.

[James Catmur]

Hardness is explained here

https://www.mineral-forum.com/message-board/viewtopic.php?p=19487#19487

Numerous ferrous minerals are not magnetic so that is not a great help

[cornz]

[cornz]

[cornz]

Further info.

It will not scratch glass, vinegar appears to be un-reactive and a sharp pointed knife will not mark it.

I've asked him to pass it over his *metal detector.

*a decent one.

[James Catmur]

Suggests that it might be flint/chert given the hardness

[cornz]

Just a quick thanks to all whom helped my friend ID his rock. He has decided to cut it open and see what it contains.
Thank you.
Cornz