Geology question

mamabear

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Jim in Idaho

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Simply being exposed isn't enough to have gems. Old rock is just old rock. Some of it has gems, some doesn't. Sometimes basalt lava brings up gems from ancient deposits. But, usually it doesn't. Same with rhyolite lava. Same with kimberlite....some have diamonds, most don't. Just have to keep looking. The best thing I've learned, in my 4-year diamond quest, is never pass up an anomaly in the terrain or geology. When your eyes sweep across a big stretch of country, look hard for anything that is different, or stands out. When you find them, search them carefully.
Jim
 

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Cariboo5

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The following sentence by Jim.."The best thing I've learned, in my 4-year diamond quest, is never pass up an anomaly in the terrain or geology."...

Excellent advise Jim....:thumbsup:......and this year with help from google earth and online reports of my area which is close to a couple of thrusts one terrain anomaly that I found has the possibility of being a strike & dip. I have also learned to look for any small things outside the normal local landscapes such as change of vegetation etc.....All the best to you on your diamond quest...
 

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Jim in Idaho

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Thanks, 'Boo....one of the anomalys I found is the drywash I'm working was pushed into an arc from it's obvious original course. This arc is about 4 miles long, and at the apex, about 1 1/2 miles from the current drywash course, is a mound. I'm willing to bet $100 that mound is the remnant of a kimberlite pipe. The pipe came up, and forced the wash into going around it. I started looking for minerals in the anthills of the area, and sure enough....lots of pyrope garnet, and chrome diopside. Both are kimberlite-indicator minerals. Your eyes are the best prospecting tool you own.
Jim
 

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waxy luster

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Jim - excellent summations on those posts.

Based on the first post - my interest is how to extract Diamonds from host rock - which is lamproite.

As to second post - I'm also most curious about your Anthill comment. Do you dig to a certain level or let Clues from the Anthill speak for itself at Ground level without disturbing the best?


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Jim in Idaho

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Jim - excellent summations on those posts.

Based on the first post - my interest is how to extract Diamonds from host rock - which is lamproite.

As to second post - I'm also most curious about your Anthill comment. Do you dig to a certain level or let Clues from the Anthill speak for itself at Ground level without disturbing the best?


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LOL.... I NEVER disturb an anthill. There's an old indian thing about not taking rocks from an anthill unless you leave something behind to replace them. Also, some of those harvester ant mounds are as much as 50 years old....digging into them would be a travesty in my mind. I make an effort to keep my karma clean. So, I just look at the surface, occasionally running my hand LIGHTLY over the surface to turn the rocks. That works well enough for prospecting. Most of the gems are too small to have any value anyway. Oh...one more thing about the anthill gems. Most of them are NOT dug by the ants. The ants gather them from the surrounding area, and haul them back to the nest....sometimes taking them into the mound. When I first started this quest, I wondered about that very thing. Did some internet research and found a woman's Master's Thesis on that very subject...really interesting. She put rings, of different-colored glass beads, at various distances around the mounds and then tracked how long it took the various colors to show up on the mound. She did that for hundreds of mounds. Also distances out to as far as 150 yards. I tried it myself on a mound out back of my house. Took only 3 hours for glass beads at 6' to show up. I also saw one ant take one into the mound. So, these anthills provide a really good way to see what minerals are in the surrounding area. This woman felt the ants were genetically programmed to bring back the heaviest object. It had to do with getting the "most bang for the buck", when factoring in the energy spent to forage. Heavier objects tend to resist weathering better, and stay on the mound longer, thus providing more "protection" for the mound. The mound is hollow and has many rooms. The ants eat seeds, and need to often dry them to prevent spouting. They dry them by moving them, into the mound when the mound is warmer and dryer than the nest. They also move the ant larvae into, and out of, the mound to maintain the correct temperature. It's vital to the survival of the nest to have the mound protected from the elements.
On recovering the diamonds...usually the host rock is crushed. I assume they crush at different sizes, from larger first, down to smaller, to avoid destroying the larger gems. I know the large pink diamond, they recovered at Argyle a couple of years ago, had some damage from the crushing process....the spokesman for the mine even mentioned it. The damage wasn't bad, but could be seen...some scratches and chips.
Jim
 

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Eu_citzen

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Quite to opposite, really mama. Younger rock is often better, keeping in mind "young" is quite relative in geology! (and also depends on what gem we are talking about)

Many gems form in "near surface" environments, like in gas pockets. Or as wall linings or even as fillers of old fractures, where ever there is space available to grow.
John Sinkankas book "Prospecting for gemstones and minerals" describe this in an easy to understand way and more detailed to.
 

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mamabear

mamabear

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Thanks everybody for your replies. I will study the geo of MO & see where it leads me.
 

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