Need Help! Any Geologists out there?

mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
I appreciate any ideas here. I was detecting and panning for gold up in the San Gabriel mountains a couple of years ago with my son, and my detector sounded off like crazy over a very large rock (about 2ft in diameter). I assumed it was granite, typical white rock with black specks, and super heavy. But I could be wrong. I pushed the rock around to different spots on the ground just to make sure I wasn't catching something NEXT to it.. but no matter where I moved it.. the detector went crazy. I tried researching online any kinds of metals thay may be found in granite rocks... but so far nothing. So if anyone has had any experiences like this.. or any ideas, it would be great. I am planning a trip back with my truck... maybe I can find that same rock and break it up if there's anything worth while inside!

Thanks!
 

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Jason in Enid

Gold Member
Oct 10, 2009
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I'm not a geologist, but I did stay at a Holiday Inn one night. :laughing7:

Solid white with black flecks? Sounds more like quartz than granite. Could be lots of things setting off the detector. Take a sledge hammer to it and break it apart and re-scan.
 

smokeythecat

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Nov 22, 2012
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I collect rocks. First, find out what was mined in the area and determine what kind of rocks are around. Sedimentary, Igneous, etc. Could be a lot of stuff in your rock, but it will have to be broken to find out. Pegmatite minerals (simply and generically stated), will have quartz and feldspar in it. The metals could be most anything, including copper, gold, titanium (rutile), iron (ilmenite, pyrite, hematite), and on and on. Don't bet on gold, though. I get some of the same things here on the east coast and it's mainly iron compounds. Interesting they don't discriminate out.....
 

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mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
When I think quartz I think Large crystals.. this was a huge rock... rough texture. And I forgot to mention this was in a dried river bed with hundreds of similar rocks around... I tested about 20 other rocks that looked just like this one, but none made the detector go off. I had a very small rock hammer but all it did was make some superficial scratches. Like I said, im planning on going back, this time WITH my sledge hammer... and if I can find it again im breaking it up!
 

Moonrover

Sr. Member
Jul 17, 2012
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Does it look like this?



image-1516226413.jpg

If so, then it is diorite.

M
 

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mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
It was close.. just more white. But like I said.. it was the only rock of that exact material that made my detector go off. so it had to gave something specifically in that one rock and not a basic material of that TYPE of rock. Just curious what could form inside that kind of rock.. guess I dont have enough info... when I go again I will definitely take some pics. Ill go online and see if I can find something similar.
 

maipenrai

Bronze Member
Nov 11, 2010
1,151
242
Thailand/Europe/California
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Excalibur 2 1000
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Well, if you dont get the rock broken up, to find out what is in it, then at least get pics, and maybe you can even bring back a similar rock, to find out exactly what it is.
 

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mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
I just did some quick internet research and the mountain range I was at is largely metamorphic rock such as granite and gneiss... and fron the pics I saw, it looked a lot like the gneiss, more ths n the granite, although they're very similar. But still no luck on any kind of precious metals that could be found inside. I guess Im just going to obsess over it until I go back!
 

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mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
It was my son's beginner detector... called a bounty hunter something.. I think. I had the trash eliminator on high.. and had actually found a couple coins about 5" deep with it that day. It only has a needle indicator, its not digital, so I never paid attention to that, I was going by the strength and tone of the beep. And it was solid. It was as loud and constant as if there was a tin can about 2" under soft dirt.
 

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mdhunter

Greenie
May 12, 2012
13
1
So Cal
Primary Interest:
Metal Detecting
Moon.. the reason I dont think that's it is because this one large rock was the only one out of at least 20 other rocks I went over that were exactly the same. If it were just the basic material that was showing on the outside they all would have made the detector go off. Not even the slightest hint of a tone from any of the surrounding rocks and this one was just making it go crazy. Just dont know if there are any typical precious metals that may form within that type of rock.
 

Keppy

Gold Member
Nov 19, 2006
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To answer this question for you with out any pictures........ Is like a blind person trying to read a book in the dark.... So i will not even try............All the answers you got so far are probably wrong...............Except for ..Jason... he gave you the right answer..... I did hear from someone he did stay in a Holiday Inn one time....
 

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