Sounds like a Hot Rock to me too. Magnetite, Iron Ore and even Hematite show up on the detector as
a so called 'Hot Rocks' ... along with a few other specimens. The one you found is very similar to those
here in New South Wales, Australia. If you're in the Gold Fields, the iron ores are very often directly
associated with gold so the Gold Fields tend to be highly mineralized and hard for other detectors to work on.
When you see Gold Specimens attached to quartz, you may notice the quartz is often a reddish brown.
This is from the iron and any oxidizing from the iron ore. (see example below)
[attachment 80853 IMG_0197.jpg]
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Gold Specimen mixed with Hematite & Iron
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Those rocks like the one you found can be large or small. When you split them, the signal gets fainter in the smaller pieces.
Sometimes it's iron stone or rock with iron ore. The rocks themselves are quite boring and almost look like gravel
or even sandstone only darker. Quite hard to break with the pick axes.
A ground-balance usually solves the problem for me and the X-Terra will still pick them up but
with a much fainter signal as the bits get smaller. In Coin-Relic Mode, they should show up in the far negative (eg -
[attachment 80852 IMG_0199.jpg]
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Slag from a miner's crucible/smelter
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I've also found some rocks that are quite light - very much like pumice. (see pic above)
And these give off a signal just like metal. Turns out they were the slag remnants of a silver mine that had been scraped from
the crucible/smelter and left on the ground to cool and harden.
Cheers,
Marco
