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Advice On Identifying Minerals Within Quartz


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Hi Everyone,

I recently found a bunch of decent-sized quartz when hiking in Wales, UK. My guess is that these had been left over by an old mining operation from around 100-200 years ago and moved from their original location due to erosion (they were laying on open ground, covered in mud).

I've had an interest in collecting rocks and crystals since a young age but am unable to identify the mineral type/s. Originally assumed it was iron but none of them are magnetic and when tested with a test kit from a local store, I couldn't find any trace of lead on the rocks either.

Is it possible that the mineral is Galena or Silver or something else? (the local mine was an abandoned Lead & Silver mine)

Thanks for any help.

Leon

1) Small_1oz.jpeg

2) Grey_5oz.jpeg

3) Grey_specks_1lb_2oz.jpeg

4) Rusty_with_black_blobs_1lb_2oz.jpeg

5) Rusty_close_up.jpeg

6) Metallic_specks_1lb_7oz.jpeg

7) Metallic_specks_close_up.jpeg

8) Tall_2lb.jpeg

9) Tall_close_up.jpeg

10) Large_over_5lb.jpeg

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A lot of the surface stuff is just lichen. The first rock has a mineral in the quartz, but it is hard to identify anything looking at weathered surfaces. At a minimum, a very good closeup needs to be posted of the first rock. Better yet, break it in half, and post a closeup of the exposed surface.

The mineral has a reddish cast, and appears to have some translucency, but that could very much be just surface weathering and reflection. Vaguely reminds me of cassiterite - tin oxide.

A good cheat is to find a geologic report on the area where the rock was found, and see what minerals are found in the area. That can narrow things down sometimes.

https://museum.wales/mineralogy_of_wales/

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Thanks for info - I would have never guessed the dark markings were mostly lichen! 

The local area is known for Silver, Lead and Zinc but it does look very similar to tin oxide & quartz when I look online.

I'll have a go at breaking up some of the smaller pieces and see what shows up.

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  • 2 weeks later...

After sorting through the rocks I've collected from the area and putting aside any with lichen, these look they definitely contain minerals.

I'm assuming all of them are cassiterite - it's very flaky / crumbly when struck and leaves behind a shiny surface? The color is dark red / black and a lot of the nearby quartz is orange. The blue in the photos is not there when looking with the naked eye. Is it usual for this to erode with the weather as it's not as hard as the quartz or stone?

There is also a blue spot (the last photo) which I'm guessing is Galena based on the color and shape? The area is famous for Lead mining. I've not tried breaking this rock in order to avoid making any lead dust.

1) Rocks w minerals.jpeg

2) Tall Close 1 indoors.jpeg

3) Long Close 1 indoors.jpeg

3) Tall Close 2 outdoors.jpeg

4) Long Close 2 indoors.jpeg

5) Long Close 3 outdoors.jpeg

6) Top Close 1.jpeg

7) Blue spot close.jpeg

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