Anyone ever has seen this kind of ore before?

[Marcel]

I collected these specimens from an old mine in our forest. After some research, I found that mines in my area historically supplied:

• Lead (Pb)
• Silver (Ag)
• Platinum (Pt) (small amounts)
• Copper (Cu)
• Large amounts of Lithium (Li)

The interesting part is that my metal tester clearly identifies Pt in the black material and Au in the red material. This suggests that the ore is electrically conductive and may contain enough platinum or gold for the current to pass through. However, this doesn’t necessarily mean there's a large amount—just that these elements are present and conducting. The metal tester always detects the best conductor in a compound, so these could just be minimal traces. Another theory is that the high lithium content might be influencing the readings.

These mines have been in use for hundreds if not thousands of years. The Celts and the Roman Empire exploited them, and mining continued into the medieval ages. These are rocks that I collected directly from a vein.


I had an XRF analysis planned, but the person who offered to help hasn’t contacted me back for three months now.


I’d like to ask the mining experts here:

• Do you have any idea or assumptions about what this material could be?
• Could the presence of lithium or other elements be affecting the conductivity readings (Since several metals are present due to the metal series)?

Additional Observations:​

• Location: Found in an abandoned mine in the Taunus region, Germany, known for lead and silver mining about a century ago.
• Composition: Mostly quartz, which doesn’t dissolve in anything except HF.
• Texture & Reactions:
  • The black material is rather soft. When heated with a flame, it turned red.
  • The red material is brittle.
  • It dissolved in HCl and nitric acid, but stannous chloride tests showed no visible signs of precious metals.
  • Some undissolved residue remained, but only a very small amount.

I haven’t been able to analyze it further—any insights would be greatly appreciated!

(If you are wondering about those holes: I drilled them using wood drills to obtain some powder for tests)

 

[goldshark]

The only way to find what is in the rocks, is to do either an ICP, AA, or for just metals, a fire assay. All a continuity tester is checking for is continuity. There is no way to test for specific elements with a multimeter, unless the element is pure, and with a very tight tolerance cross section.

 

[4metals]

I have moved this thread into the Rocks category because right now that's what they are!

 

[Martijn]

I can't help you determine your rocks but it sure is an example how to provide the best info to get an answer.

I would be really careful with acids on the rocks. They look a bit like cinnabar. But could be a red lead oxide or salt.
If you have that dissolved in HCl, you could test if white salts dissolve when heated in solution, or after filtering precipitate out when cooled.

HCl will not dissolve any precious metals, maye some Pd.
A stannous test after nitric will only show silver or Pd, but any gold or Pt will stay in solution. You need pretty strong and hot AR to dissolve Pt.

But I am not experienced with ore. So it could be anything. Be carefull.

Geology of the area with mine site data:
https://www.mindat.org/loc-23882.html

 

[Martijn]

From what I read your tester is for metal only. Not for rocks with minerals.
https://en.adrenalinemedia.de/product-page/kopie-von-metall-tester-bozz-tech-mti00x-v2

 

[Marcel]

@Martijn: It is the first time I have found a rock that is so highly conductive. Usually, rocks and stones do not conduct electricity at all.
I had an inquiery from South Africa where a company wanted me to develop a low cost version for the use in mines. I told them that this would not work, but decided to give it a try and collected my samples. I have no other ores so that was the easiest way to do it. But I am quite certain it will not work on a typical gold ore. Never said it would!

If anyone reading this post is able to perform a professional fire assay or another suitable method for analyzing ores, please PM me—I can send a sample.

I know there is a lot of lead and lithium in the rocks in our area. To me, the colored parts look like litharge or another lead oxide. Together with lithium and humidity, that could create some sort of natural "battery."

I have seen some videos on YouTube where people in Africa held LEDs against rocks, and the LEDs lit up. I always thought this was a scam (Most of these videos are trickery), but now I’m not so sure if it may not be possible under certain conditions.
If the right mix of metals is present in a rock, it might actually be possible. All in all I measured a voltage of around 1.5V But the maximum current is far to low to make any LED glow.