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#1

Bjay
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Joined: 22 June 2015
Posts: 763
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28 December 2015 07:47 pm

1451292156_image.jpgfound a couple of thes rocks today while out panning. I took the sdc with me just to run over my sieving s but no luck but these rocks made the sdc sing. Not like the normall hot rocks I find as there a defiant e target but can't see any metal in them and there only very faintly magnetic so any ideas would be greatly appreciated.

#2

silver
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Joined: 19 December 2013
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28 December 2015 08:14 pm

you might need to post an outside of rock photo too Bjay,.... for all our mineral connoisseurs. tongue


What a great day ! ,... " I'll see you in the field ".

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#3

Bjay
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Joined: 22 June 2015
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28 December 2015 08:27 pm

I'll try , took me an hour to try to get the first one up but I'll persist

#4

silver
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28 December 2015 08:31 pm

Don't sweat over it Bjay,...we all got plenty of time,... next week will do if you like. big_smile


What a great day ! ,... " I'll see you in the field ".

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#5

Bjay
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Joined: 22 June 2015
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28 December 2015 08:34 pm

1451295162_image.jpgi think I finally worked out how and remembered it . Also got a couple of small stones but for a different thread .

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#6

silver
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Joined: 19 December 2013
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28 December 2015 08:50 pm

To me from here it looks like basalt(blue road metal),... basalt rocks at the beach but up in the dirt layer get an outer coating like that,...even in land further they get like that Bjay.( I may be wrong of course). wink big_smile


What a great day ! ,... " I'll see you in the field ".

#7

Bjay
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Joined: 22 June 2015
Posts: 763
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28 December 2015 10:37 pm

Phone went flat. Yeah I thought the same. Why's the sdc scream at it though?

#8

silver
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Joined: 19 December 2013
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28 December 2015 10:52 pm

That Bjay is a complete mystery to me,...but others on here might be able to enlighten us both. big_smile


What a great day ! ,... " I'll see you in the field ".

#9

silver
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Joined: 19 December 2013
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28 December 2015 10:56 pm

When I am detecting at the beach the basalt rocks show up(only certain ones of them) on the ACE250 in pinpoint mode,... but the same rocks will not give any signal at all when you let the detector do the analysing,.... so I'm guessing that these same types of rocks when they reduce would contain some of the black sands that we find along our volcanic parts of the eastern Australian coast.(once again,....maybe). big_smile

Last edited by silver (28 December 2015 10:57 pm)


What a great day ! ,... " I'll see you in the field ".

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#10

Bjay
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Joined: 22 June 2015
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28 December 2015 11:26 pm

They just gave that sdc squeal that tells ya that your Going to find a target no matter the type of rock but didn't happen. Still interested why though

#11

silver
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Joined: 19 December 2013
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28 December 2015 11:33 pm

me too,... although I learned to discern them at the beach,... if the target analysis shows something there as well, then there is definately a target under the rock(with the ACE) big_smile


What a great day ! ,... " I'll see you in the field ".

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#12

mbasko
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From: Central West NSW
Joined: 27 January 2015
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29 December 2015 12:15 am

Looks like a type of basalt to me. Some types of basalt will signal (sweetly) on a detector. Even though they seem to have a weak or no magnetism various types of basalt can have a high iron content - this is why the outer layer of an otherwise blackish rock is brown/rusty.
The iron content in different types of basalt & basalt in different areas can vary widely - this is why some signals & some doesn't; some areas are prone to high iron content basalt all over; some areas have a few that signal but most don't & other areas don't give much if any trouble at all.


Everything we use comes from mining or farming.

5 users like this post: Bjay, Heatho, silver, AtomRat, blisters

#13

AtomRat
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From: Katazone, VIC
Joined: 22 May 2014
Posts: 5,075
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29 December 2015 06:26 am

It the rocks not attached to you I'd crush it and pan to see what heavies r inside so u know.


Wisdom is knowing how little you know

1 user likes this post: silver

#14

Bjay
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Joined: 22 June 2015
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30 December 2015 09:44 am

Thanks for the explanation guys. Never come across basalt while detecting before so I have learnt something new. I think I will crush it just for piece of mind.

1 user likes this post: silver

#15

jethro
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From: North East , VIC
Joined: 06 September 2013
Posts: 349
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30 December 2015 05:25 pm

What area of the state did you find it in BJ. I dont have much experience with basalt under the detector, and no experience with the sdc. I think Mbasko has pretty well nailed it though.

#16

Bjay
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Joined: 22 June 2015
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30 December 2015 09:12 pm

Gippsland region only reason I took the sdc was I got a picker almost completely covered with ironstone and thought Maybee I could have missed one in the sieve. No luck though. Yeah pretty happy with mbaskos explanation. Not something I ever had experienced before.

#17

Flitgold
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Joined: 11 June 2015
Posts: 28
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20 April 2016 05:51 pm

Mate thats looks like a typical weathering rind of a basalt and its fine groundmass certainly suggests it too!
Basalts are generally weakly to strongly magnetic due to ferromag mineral content

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