Some Stupid questions?

[MadMarshall]

I have a few questions that I am having trouble coming up with the answer too

1. Why do I get a very strong gunpowder smell when hammering on some Rocks.
2. Over time Cracks widen but do they get smaller over time as well..
3. Gold with red stains.. I was wondering if stained gold was a sign of more recently shed gold.. After time does nature and the river clean the gold. Or being exposed to air? or does it always stay stained?
4. Stockwork veins.. Any information all information...
I appreciate the help

 

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[caprock]

stockworks often form in the hanging wall of a mineralized vein,the type of rock determines if a stockwork forms. If a rock is brittle, it will shatter along a fault creating a zone where a stockworks will form. If rock has been previously silicified it is a prime candidate. If a rock acts like a sponge and soaks up hydrothermal fluids it will not form, like gray ore in Mother Lode. Large discreet veins often grade into a stockworks zone and back again. Where the stress are concentrated along a fault, and depth of deposit formation also effects formation brittle vs. ductile deformation . Hope this helps

 

[dave wiseman]

The gunpowder smell might be from the sulphurants inside the rock...

 

[timberjack]

I had the gunpowder smell with this rock, it also sparked when you hit it with a hammer, the black sections did not really scratch with my knife, part of the rock (very black part) is magnetic. When broken with a hammer the black sections had a kinda silver-black metal look to it. I looked it up in some rock books and figured it might be arsenopyrite, a sulfide (arsenic and sulfer) ..sent it off for an assay any came back as arsenopryite and hemmitite...in a quartz vein..if you heat arsenopyrite with a torch it becomes magnetic (makes a very toxic glass in the process) but will help I.d. it...don't know about the rest but very interested in the subject

 

[MadMarshall]

Thanks gentlemen
Dave I do not believe it is the sulfur but I can't say for sure Why not the Rotton egg smell?
When I first asked myself this question I looked up what makes blackpowder/gunpowder to see if would help. Can't say it did.

Caprock thanks I will be reading up on brittle vs. Ductile and continuing trying to learn... I was wondering if you might have a link to a sample picture of Stockworks veins I am having a hard time visualizing it.

THANKS AGAIN EVERYONE

 

[caprock]

Waldemar Lindgren's book Mineral Deposits is a great place to start, excellent graphics and descriptions.
Lindgren is one of the fathers of economic geology, and his works are hard to beat.
Available online at archive.org

 

[timberjack]

"Fists full of gold" by Chris Ralph is a book that covers the basics..and very well written...if I could just retain all the information in there I would be all set..

 

[dave wiseman]

When the sulphides are exposed to water or soaking in water you get the rotten egg/sulphur smell.

 

[TerryC]

Water action on course gold DOES clean it. The % of silver in small nuggets gets LEACHED out, making the very small nuggets of an area more pure than the hillside veins they came from. Those with more expertise than I will answer the other questions. TTC