Red Dirt and Desert Gold?

[Hard Prospector]

The areas I prospect in the southwestern deserts, most of the gold/quartz deposits seem shallow and almost always iron oxides or iron stone is present. Where the host rock of the district is granite, when I start seeing iron stone strewn about I've learned to slow down and be through. Areas of bookshelf schist with crusty mineralized quartz veins get worked over with my PI and VLF machines til I'm satisfied. I know of guys who have found nuggets in iron oxide "blow outs" or seems of this red fine grained powdered stuff so as the saying goes, gold is where you find it. These are just personal experiences, I'm no geologist...........Rob

[tvanwho]

Rob,

 

What is this Blowout thing? Got any photos of this or the iron oxide seams that had gold in them? One of the YouTube gold videos I watched, the guy was panning gold flakes out of something called Limonite and it was dark red material by an old gold mine. He had to bust it up with a pick and drill first. Is iron stone just black rocks like magnetite that sticks to a magnet?

 

-T

[Reno Chris]

A blow out is a term for a pod or blob of other material in rock - as opposed to a long and narrow vein. Quartz or iron minerals are common things to find. Sometimes pegmatites can form this way too.

Limonite is an iron oxide. It can yellow to orange and even brick red. In quartz veins, Limonite can form from the decomposition of pyrite by weathering. If there was gold in the original pyrite there will be gold in the resulting limonite.

[Steve Herschbach]

But those who have been engaged in practical mining for long, finding by experience that no two mineral fields are exactly alike in all their characteristics, have come to the conclusion that it is unwise to form theories as to why metals should or should not be found in certain enclosing rocks or matrices. Some of the best reef gold got in Victoria has been obtained in dead white, milky-looking quartz almost destitute of base metal. In South Australia reef gold is almost invariably associated with iron, either an oxide, as " gossan ; " or ferruginous calcite, " limonite; " or granular silica, conglomerated by iron, the " ironstone " which forms the capping or outcrop of many of our reefs, and which is often rich in gold.

But to show that it is unsafe to decide off-hand in what class of matrix metals will or will not be found, I may say that in my own experience I have seen payable gold in the following materials :—

Quartz, dense and milky, also in quartz of nearly every colour and appearance, saccharoidal, crystalline, nay, even in clear glass-like six-sided prismatic crystals, and associated with silver, copper, lead, arsenic, iron as sulphide, oxide, carbonate, and tungstate, antimony, bismuth, nickel, zinc, lead, and other metals in one form or another ; in slate, quartzite, mica schist, granite, diorite, porphyry, felsite, calcite, dolomite, common carbonate of iron, siliceous sinter from a hot spring, as at Mount Morgan ; as alluvial gold in drifts formed of almost all these materials ; and once, perhaps the most curious matrix of all, a small piece of apparently alluvial gold, naturally imbedded in a shaly piece of coal. This specimen, I think, is in the Sydney Museum. One thing, however, the prospector may make sure of : he will always find gold more or less intimately associated with silica (quartz) in one or other of its many forms, just as he will always find cassiterite (oxide of tin) in the neighbourhood of granite containing muscovite (white mica), which so many people will persist in terming talc. It is stated to be a fact that tin has never been found more than about two miles from such granite.

From what has been said of its widely divergent occurrence, it will be admitted that the Cornish miners' saying with regard to metals generally applies with great force to gold : " Where it is, there it is" : and " Cousin Jack" adds, with pathetic emphasis, " and where it is generally, there I ain't."

 

From GETTING GOLD: A PRACTICAL TREATISE FOR PROSPECTORS, MINERS, AND STUDENTS.
BY J. C. F. JOHNSON, F.G.S., 1897

[tvanwho]

And can you experts, Chris, Steve, Jonathan,  tell us how the old timers got their knowhow of where to dig for the gold? I thought they were mostly get rich quick types as in the gold rush at Pikes Peak, Colorado where the saying was " Pikes Peak or Bust" and shortly afterwards the saying was" Busted, by Golly" , as they came back east...and yet they seem to have done quite well in the American southwest deserts and California/Nevada goldfields. Who were these guys anyway? They had no historical precedents to go by in 1849 or knowledge of hardrock gold until later on. Was it all just dumb luck and perseverance that  they found the yellow metal?

 

-T

[Steve Herschbach]

They were every bit as smart as us Tom. They read books, used trial and error, observed results, compared notes, wrote more books, knowledge spread. Same story of human progress told over and over again. And you say no historical precedent? People have been prospecting since before recorded history. De Re Metallica was published in 1556 and would tell much of what you would need to know today. Prospecting was old news by the time we got around to it in the United States and most of the best prospectors and miners were people from other countries with prior experience.

 

During the gold rush lay people just like us had plenty of books they could study. Or they could just rush off on dumb blind luck and go broke which plenty did then and still do now.

[azblackbird]

De Re Metallica was published in 1556 and would tell much of what you would need to know today.

 

Came across references to that book when I was doing research on refining. Amazes me how little has really changed.

[tvanwho]

Hmm, interesting, maybe I should actually read my De Re Metallica book and get some insights.

 

-T

[tvanwho]

I found a COOL website that shows several color photos of Gossans including one laced with GOLD. They are large rusty iron caps produced when iron pyrites are exposed to air and water and the rusting process begins. I even found out they can catch on fire due to heat produced in the oxidation reaction. Apparently the copper mine at Jerome, Arizona had an underground fire due to this phenomenon. I also just learned from watching a Jeff Williams seminar on YouTube, that the Vulture gold mine in Arizona, was found by Henry Wickenburg  as a result of his examining a RED Iron gossan cap he found on Vulture Mountain. His samples were loaded with visible gold it seems.

 

-Tom V.

 

http://au-prospecting.blogspot.com/2013/02/gold-and-gossan.html

[Reno Chris]

And yet there are big gossans in Nevada with only tiny traces gold - they have more silver, lead and base metals.