What is this rock?

[sjb]

I am stumped with this rock. I have never had a rock cause such an overload on my metal detector. I have a new Minelabe Safari and took it to the beach. It signaled gold and of course we dug, dug dug. About two feet down, there were rocks, and we took them out of the hole one by one. This rock was the cause of the beeping- and every time we test it, it causes the machine to "overload" with such a strong signal. The dark grey color of the rock rubs off on our hands, and we can write with it (like it is graphite or something). There is a vein of quarts and shiny material that runs through the rock. Any thoughts?

http://s994.photobucket.com/albums/af66/sjbgarden/Rock/

Thanks!

 

Amazon Forum Fav 👍

Family Maps of Hinds County, Mississippi, Deluxe Edition - Grab it through Amazon!

[High Plains Digger]

I grew up in Grass Valley, and played on the rock dump of the Empire mine, about 100 yards from our house. Just fine grained granite there. I have no experience with graphitic schist. I am learning with every post.

 

Amazon Forum Fav 👍

A Handbook of Civil War Bullets and Cartridges - Grab it through Amazon!

[Tuberale]

Granite is metamorphically altered limestone. Quartz and mica are usually formed at extreme depth in the Earth's crust. But graphitic schist didn't get that deep, so didn't have as much heat to alter the mixture.

Oil is carbon. Coal is carbon. Oil shale has carbon. Diamond is carbon. All formed at different depths and therefore at different temperatures.

Pressure (weight on top) of rock overburden also affects how much rock can be changed/altered.

Hope that explained some of the questions. I'm still not a geologist, but I have had a few classes ...

 

[kuger]

what ever the case,that pocket was VERY rich,and that Graphitic schist is something else!!I still remember my alarm at the fact my hands werent coming clean...then two days later I was really starting to become concerned!!

 

[sjb]

Mica and gold can go together. It is the graphite that I don't understand, and how it got thown into the cake mix. Whether it came from coal or if there is something as "elemental carbon" , I just don't know, and how it got into ingeous rock. But diamonds are carbon, and are in ingneous rocks.

Not sure either,but there are belts of it(Graphitic schist)here in the Gold Country,and in the mining reports it states "Gold associated with Graphitic schist in such and such area",I didnt know anything about it until,my hands were stained black from it,and scared me when I couldnt get it off!!Then did a little research,and have always kept an eye out for it since!!

One thing- the discoloration from handling this material easily washes off- and does not feel oily or anything, more like soft pencil markings (graphite).

 

[sjb]

By the way, I will happily send some of this to anyone, free of charge, who might feel the identification is incorrect. I love to learn, and this is way over my head. The man who looked at it spent just a few minutes, so you never know. I did not attempt to open it up any more.

I put fresh batteries in the old Bounty Hunter I have and it screamed at even the smallest piece, so the whole thing is reactive.

 

[kuger]

Mica and gold can go together. It is the graphite that I don't understand, and how it got thown into the cake mix. Whether it came from coal or if there is something as "elemental carbon" , I just don't know, and how it got into ingeous rock. But diamonds are carbon, and are in ingneous rocks.

Not sure either,but there are belts of it(Graphitic schist)here in the Gold Country,and in the mining reports it states "Gold associated with Graphitic schist in such and such area",I didnt know anything about it until,my hands were stained black from it,and scared me when I couldnt get it off!!Then did a little research,and have always kept an eye out for it since!!

One thing- the discoloration from handling this material easily washes off- and does not feel oily or anything, more like soft pencil markings (graphite).

Well put it in water and mix it with some natural clay.......just shared my one experience with it....sorry

 

[High Plains Digger]

Whoa----granite is absolutely igneous. The size of the crystals in granite depend on the time it takes to cool down. Not even a close cousin to limestone. Limestone is sedimentary, all day long.

 

[kuger]

Whoa----granite is absolutely igneous. The size of the crystals in granite depend on the time it takes to cool down. Not even a close cousin to limestone. Limestone is sedimentary, all day long.

Thats absolutely correct,I wasnt gonna argue

 

[EagleDown]

Just thought I'd throw my 2 cents onto the rocks.

The third ingredient in gun powder is "saltpeter", which in natural form is called "Sodium Nitrate".

 

[fountainofyouth]

Has anyone considered it to be a radioactive rock!! There are many varieties like Uraninite.
Radioactive rocks are often grayish and can explode when any type of heat is applied.
It leaves a black streak. Its not magnetic. Makes the detectors run wild.
I could be wrong. If its that you surely would not want to mess with it!

 

[EagleDown]

And, the sudden compression of a hammer blow would generate heat.

I haven't messed with pitchblende since 1954, and then I wasn't really all that interested. Anyway, it's been so long that I had totally forgot about it.

fountainofyouth, you might be right!! I just looked up pitchblende in wikipedia, (briefly,) this is what it has to say about it:
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements. It is most commonly known as pitchblende .

I think I need to go back up to Mariposa with a geiger counter.