Jump to content
Nugget Shooter Forums

Question for the "rcok hounds"


Recommended Posts

OK, being new to Nugget shooting/Metal detecting, I have a question. I was out around Tumacacori today. Yeah nothing but bullets and junk, but it was a beautiful morning and I was ok with that. But I found some quartz and it just looked like the average quartz I have seen before in other places. Now the Quartz I an talking about is the set of 3 at the top of the picture. :icon_mrgreen:

But then I went somewhere else not to far away this morning and found what looks like quartz, but is totally different looking. It is very smooth and in what looks like buds. There are 2 of them at the bottom of the picture. Now I didnt find any gold and the hunters were out and about, but as I said, it was a sweet cool morning and I was at that point happy to be alive. :headphones:

But does anyone know the difference between the 2 and is there a type of quartz that gold is more prevelent around? I know that might be a hard rock mining question eh? :laught16:

post-21685-1227992525_thumb.jpg

Link to post
Share on other sites
Looks to me like the top 3 are indeed quartz with various inclusions and the bottom 2 look like Chalcedony (agate) If I am wrong someone please correct me...

You're correct :D Chalcedony is identified by it's milky like presence, and it usually looks "bubbly". It is formed like Quartz but does not reach the high temperatures that good crystal Quartz does. You can usually find a lot of "bubbles" in it and the "bubbles" are small round shaped pieces. The good news is that sometimes crystal Quartz is nearby, and of course that is a possible mineral location.

Link to post
Share on other sites

Thanks guys, OK then you confirmed my suspicions. Too many hunters around and I dont wanna get shot, but the whole area looks very promising. :innocent0009: At this learning stage fopr me, I appreciate everyones help.

Link to post
Share on other sites

Many colors and kinds of quartz abound in any gold bearing areas,from vuggy,milk white,rose,sandwhich,glassy,bull blue-black-gray of the east belt motherlode,limey and porcelin like quartz,etc....In one mining district one or more may be prevalent.The most promising looking quartz whether float or in situ may be totally barren.As with anything if a fellow sees something unusual an investigation is usually made,curiousity,basic human nature can sometimes lead to a good find.

Link to post
Share on other sites

That "Vuggy-Rusty quatrz" with crystals in it is a favorite of mine. There is a place at Date Creek, AZ where you can dig overgrown,double terminated and 'Secpter" quartz crystals from little pockets filled with rusty black sand and fine gold. I never found any gold there that was not dust but it was originaly developed as a gold mine and had a vertical shaft and a horizonal shaft which have been filled in. Now picked over by the crystal collectors.

post-7251-1228047493.jpg

Link to post
Share on other sites

Max-

Was over around Date Creek many times and was aware of the really fine gold in the creek itself but was never aware of any double terminated crystals being found in that area! There a really small "patch" in that vicinity that still has some small gold nuggets in it but it's been so long since I've been out there- I doubt if I could find it anymore.

Steve

Link to post
Share on other sites

Date Creek....hmmm

Hey if there is fine gold in the creek are you panning any? :confused0013:

Link to post
Share on other sites

Steve,

I'll give up a little secret: Crystal diggers some times don't know that the pockets that grow crystals have gold in them too.

In the case of Date Creek the diggers have busted lots of the formation to find the pockets typicaly containing 1 0r 2 crrstals and a hand full of black/rusty dirty sand, they just ingnore it and it eventualy works its way down in the tailings, since you and I lived at Stanton they have dug at least 15 feet of fairly solid rock formation, the tailings filling a vertical shaft that was particily open in 1983, there may be others I was not aware of.

There was still a small horizonal tunnel when I was last there but it may have been dug by crystal hunters.

All the gold I found there was very fine dust but I was mainly interested in the crystals and did not explore outside the pocket area we were getting overgrown septers in.

Its an unusual area.

Sonnysnewlife, I doubt that any water stays in Date creek long enough to pan, most of that area is flats and it flash floods and then disapears for another year, there are " Iron Caps" and volcanic stuff near by.

Max-

Was over around Date Creek many times and was aware of the really fine gold in the creek itself but was never aware of any double terminated crystals being found in that area! There a really small "patch" in that vicinity that still has some small gold nuggets in it but it's been so long since I've been out there- I doubt if I could find it anymore.

Steve

Link to post
Share on other sites
Guest bedrock bob

Most rock sare classified by their appearance rather than their composition. Your judgement that these are made of the same stuff is correct!

Quartz and Chalcedony are made of the same stuff as glass is... silicon dioxide. Quartz has crystals that are visible to the naked eye. It was formed under pressure that allowed the crystals to grow big (intrusive, or at depth/pressure). Chacedony (desert roses) were formed near the surface (extrusive) and the crystals are very small, microscopic, like glass. Same stuff, different crystal structure. Agate is the same (silicon dioxide) but has a colored or milky appearance and was formed just under the surface at very little pressure while chalcedony was formed "at" the surface or in a pocket that had no pressure. Often a chalcedony vein turns in to agate just below the surface. Fossil bones are either agatized or opalized as well, where silica replaces the calcium of the original bone. Opal is just silicon dioxide with some water. All formed from hot acidic water carrying silica, just at different depths and in differing conditions.

Gold is generally formed intrusively. Quartz (when in a lode or vein) is usually a component of intrusive formations. Chalcedony and agate on the other hand is indicative of a volcanic (extrusive) geology. When you are talking placer it does not make much difference what the constiuents of the gravel are, because layers of geology get shuffled around in the gravel by nature. As far as the formation that the gold came in you can bet (with fair assurance) that the chalcedony has no gold. Even in gold bearing veins the gold usually is not "in" the quartz, but rather in a gangue material that has quartz in it. The classic "motherlode" quartz with gold filling is not too common in general. Even though you see nuggets in quartz, the paying part of the vein was probably more hematite or manganese than quartz. All of the gold veins that I have worked on have been a rusty red hematite gossan with scattered quartz. In other words the gold is more associated with the metals than with the quartz.

I believe the reason that a lot of big nuggets are found in quartz is that it is durable and does not weather as much. The rest of the gold is weathered out of the hematite (or whatever) and ground up to placer. The solid quartz just held it together and protected it. Only a small percentage of gold will be lucky enugh to be encased in quartz. I dont look too much at the quartz unless it is filled with bright red or brownish "chili powder" and littering the hill below the vein as float (chispas). Then I begin testing it.

You can find a heck of a lot of good looking quartz in nearly every location. Lots of black sand too. These are good indicators but just indicators. Most solid quartz is as barren as Hillary. I have found very little gold in quartz even within a rich vein. Most is in a soft hematite gossan studded with little quartz crystals. When you begin seing pyrite (sulfide) and lots of solid quartz you are getting close to water table and the free native gold will dissappear in the formation as you go down. The best indicator that there is gold in the quartz is ilmenite (I believe I got that mineral right, it could be limonite?) which is the decomposed form of pyrite. This indicates an intermediate boundary in the intrusive formation, or outright vein oxidation, which is the ideal place to find a native gold vein. Look for a contact between metamorphic and igneous rock that has silica (quartz) in a vein filling of oxidized metal ore. This will narrow it down a lot more than just "quartz", which can be found nearly everywhere in great volumes.

Again, all this means nothing when looking for placer. The only real indicator of placer gravel is gold particles.

Bedrock Bob

Link to post
Share on other sites

Excellent condensed gold geology, Bob...Thanks. I copied it to my gold research folder....Cheers, Unc

Link to post
Share on other sites

Bedrock Bob stated:

Even though you see nuggets in quartz, the paying part of the vein was probably more hematite or manganese than quartz. All of the gold veins that I have worked on have been a rusty red hematite gossan with scattered quartz. In other words the gold is more associated with the metals than with the quartz.

OK so in picking your brain a bit more. would this be "rusty red hematite gossan"? Or do you have to perform tests to tell?

post-21685-1228231000_thumb.jpg

By the way, I am always amazed at the amount of knowledge that people have. Geology while not such a charismatic study, is something that interests all little kids, but we lose it as we grow up. I think I am now in my 2nd childhood.........

Link to post
Share on other sites
Guest bedrock bob
Bedrock Bob stated:

Even though you see nuggets in quartz, the paying part of the vein was probably more hematite or manganese than quartz. All of the gold veins that I have worked on have been a rusty red hematite gossan with scattered quartz. In other words the gold is more associated with the metals than with the quartz.

OK so in picking your brain a bit more. would this be "rusty red hematite gossan"? Or do you have to perform tests to tell?

post-21685-1228231000_thumb.jpg

By the way, I am always amazed at the amount of knowledge that people have. Geology while not such a charismatic study, is something that interests all little kids, but we lose it as we grow up. I think I am now in my 2nd childhood.........

This looks like good quartz, but from my experience the hematite makes up well over 60-75% of the volume and quartz only 25-30%. This is in my area though and each is different. Remember, a small rock like this is not nesesarily representative of a cross section of a vein or ore body. There will be plenty of variation. From what I can see this is the proper type of quartz, definitely intrusive or intermediary. There will be zones that have more quartz and zones that have more hematite in any formation. You are definitely on the right track for locating the "home of gold". "Home" can be a long way from placer though.

A "gossan" is generally an oxidized, pitted, rotten looking rock that is generally held together by a latticework of quartz. At leat this is my definition and I am no geologist. Anyhoo, I would say that this rock, although studded with red oxidized minerals, would be a little too solid. The ore I am used to looks just like a cake of red chile powder. Sometimes it is browner, like a cake of nutmeg or cinnamon. Quartz would be the secondary mineral, rather than the primary in MOST of the vein. Gold can come anywhere in an ore vein, not just in the soft "nutmeg" and not just in the solid quartz.

Again, the only way to yea or nay a rock of any kind is to test it. A 20X or 30X loupe will often allow you to see gold that you just could not see with the naked eye. A lot of quartz that WILL NOT PAN and WILL NOT SHOW ANY VISIBLE GOLD wil assay well. Not somethign I want to spend time working but maybe something a larger operation could capture at a profit.

Hey, ask me anything. I just love this stuff! I like writing about it even more!

Bedrock Bob

Link to post
Share on other sites
Guest bedrock bob

And most of our gold veins here are RICH in manganese. Many deposits could not be smelted at a profit because the manganese stuck to the old iron pots at the Playas mill and made a mess. When they changed to aluminum pots just after the depression the old miners say they could turn a good profit from mines that were worthless before. At least that is what I have been told. There is less manganese in FREE MILLING GOLD VEINS, but it is in there.

I have never seen a gold vein (here) without a showing of black manganese as well as some yellow arsenic powder. Hematite and manganese seem to run together. It is natural I guess to find them in combination. The more arsenic powder the more lead and antimony you will find and base metals and silver abound. The gold seems to stay more in the veins that run copper and less gold in the veins that have the base metals. Lead veins always runs high silver and very litte gold, and if there is any zinc (sphalerite or galena) it will show silver and no gold. Not hard and fast rules but a generalization. At least on the veins that I have learned about and worked on. My rule of thumb is that if nonferrous base metals are prominent over copper, LOOK SOMEWHERE ELSE FOR GOLD, STAY RIGHT WHERE YOU ARE FOR SILVER, AND ALWAYS TIP THE WAITRESS NO MATTER WHAT THE VEIN IS RUNING.

One thing for sure is that a good showing of metals in a vein are almost a prerequisite for gold. I do know one are where gold is in a halide deposit with no other metals worth mentioning. All other areas you will find an abundance of metals in one form or the other. The trick is recognizing these as metals and not just "brown powder" or "cinnamon crystals" etc. etc.

Again, this means absolutely nothing to the placer operator. Just not relevant information to find placer gravel as most of it here shows a heavy volcanic/extrusive makeup anyway. The best indicator of a lode is mines. The best indicator of placer is placer workings. The best indicator of nuggets seems to be a firm caliche and/or false bedrock in a fairly level layer below free milling veins under stratified alluvium. I simply do not look at rocks or geology much anymore unless I am down in a mine using the beeper, and then I just follow what they did and learn from the old timers. No use re-inventing the wheel. But hey, if a rock beeps, I am all ears!

Bedrock Bob

Link to post
Share on other sites

as for black sands and the hematite you are talking about,

i think you might actually be talking about magnetite.

hematite is not magnetic,

magnetite is (hence how you can use a magnet to seperate it out of the pan)

i do some iron mining (but not much gold mining) so i might be wrong...

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...