flatlander
starting to shine!
Member since May 2007
Posts: 27
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Post by flatlander on Nov 16, 2007 10:14:43 GMT -5
I live in the centre of Saskatchewan, Canada, mostly flat, lots of gravel deposits to hunt through. Northern Saskatchewan (about 350 miles north of here) is where the Canadian shield crops up, lots of mining up there (gold, diamonds, uranium, nickel). I have a little bit of knowledge of rock identification But... If I brought home every rock that looked promising, I would need a much bigger truck. Our gravel pits, creeks, and rivers hold lots of color some dolomite, and limestone, but mostly granite. My question is how do you field identify, and cull your finds to a manageable load? When I search for rocks to tumble I try to look for ones that are hard, with a tight grain, maybe some translucent areas. What I am really looking for is some tips on what to look for . Are there indicator rocks that would identify a good place to look? Like is a gravel pit full of granite a good place to look for agates? Near our cabin there is a deposit of pure white silica sand, might there be anything either in or near the silica? Whenever we are fishing, I usually spend some time on shore, and have found some fabulous jaspers, which are easy because of their bright colors, but finding what I think are agates is just blind luck. I was to a pit in Sour is Manitoba that holds lots of Agates, and Jaspers they all had sort of a smooth but irregular surface like they were cast in a mold, but nothing like that around here. Thanks, Doug
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Nov 19, 2007 12:38:33 GMT -5
I live in the centre of Saskatchewan, Canada, mostly flat, lots of gravel deposits to hunt through. Northern Saskatchewan (about 350 miles north of here) is where the Canadian shield crops up, lots of mining up there (gold, diamonds, uranium, nickel). I have a little bit of knowledge of rock identification But... If I brought home every rock that looked promising, I would need a much bigger truck. Some people here would say you answered your own question there- get a bigger truck, or at least a trailer.... Our gravel pits, creeks, and rivers hold lots of color some dolomite, and limestone, but mostly granite. My question is how do you field identify, and cull your finds to a manageable load? Who said anything about being loads being manageable? When I search for rocks to tumble I try to look for ones that are hard, with a tight grain, maybe some translucent areas. What I am really looking for is some tips on what to look for . Are there indicator rocks that would identify a good place to look? Like is a gravel pit full of granite a good place to look for agates? You have the right ideas here too, with alluvial deposits (river gravel) like you have there, a lot of stones looks the pretty much the same to the casual observer, but subtle colors and translucency are the hints that better stuff lies within. Up on the shield as you mentioned, bedrock is at the surface and localities with veins and such reflect the geologic conditions that form the rocks, and are how things get cataloged, but because the rivers have carried your gravel from hundreds or thousands of miles away, any local concentrations were redistributed thousands of years ago, you just need to sift through more to find the good ones. Near our cabin there is a deposit of pure white silica sand, might there be anything either in or near the silica? Whenever we are fishing, I usually spend some time on shore, and have found some fabulous jaspers, which are easy because of their bright colors, but finding what I think are agates is just blind luck. The differences between jaspers and agates are pretty subtle, there are quite a few "jasp-agate" localities here in the US, so don't get too terribly hung up on the distinction, in beach collecting especially- its nearly all blind luck, and in the end nice rocks are nice rocks. I was to a pit in Sour is Manitoba that holds lots of Agates, and Jaspers they all had sort of a smooth but irregular surface like they were cast in a mold, but nothing like that around here. Thanks, Doug Again probably closer to basement rocks and local to some pre-historic volcanic activity- you would expect to find concentrations like that, where specific geologic phenomena created the rocks there, but eventually as the rivers cut through and move stuff around- to places like central Saskatchewan, they'll get mixed up with everything else.
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Nov 19, 2007 16:07:44 GMT -5
Much of Saskatchewan is covered with glacial till so you will see a lot of granite from the Canadian Shield throughout the province. Some of this makes okay tumbling material, but avoid the ones with black specks, as this is often biotite mica and it will form pits when tumbled because it is softer than the quartz and feldspar in the rest of the stone. You should also find pure pink or red orthoclase feldspar, and pure pieces of white quartz, both of which are fine for tumbling. If you are finding dolomite and limestone then you in the old sea sediments in the south half of the province. Neither of these are worth tumbling because 1) they are usually bleah colours, and 2) they are only about mohs 3 in hardness so won't take a shine (compare that to mohs 6 for feldspar and mohs 7 for quartz). I don't think you will find true agates in Saskatchewan. The Souris agate beds in Manitoba I believe are old sediments washed in from the northern US, as they seem to be identical to Montana agates, at least in any pics I've seen. The smooth exterior to them is probably from being river-tumbled. There are supposedly agates in the Hand Hills of central Alberta, but the few I've seen are not very colourful. Some rock club in Calgary does or used to run collecting trips to the Hand Hills to look for the agates, among other things. I think they are mainly of note because the natives used to use them to make arrowheads. There might be something similar in Sask., but I'd only be guessing. As for indicator rocks, I don't think there is anything like that to tell you that you are in a good area. I think your best bet is to either hit gravel pits like you've been doing, or check out the river gravels of either the North or South Saskatchewan rivers. The advantage of river-hunting is that the rocks are either wet or near enough to water that you can easily wet them to see their true colours. I don't know exactly what these rivers will have in them, but my guess would be a mix of Canadian Shield rocks, quartzite from the Rockies, and probably petrified wood. The advantage of being a fair way from the Rockies is that most of the softer materials will have broken down before reaching Saskatchewan, so mainly the hard stuff is all that will remain, apart from local materials. Quartzite is extremely common in the North Saskatchewan in Alberta, in fact it makes up something like 90% of the river gravels. Mostly it is dull and unappealing, but if you search a bit you will find colourful little nuggets that are coloured by iron oxides. Plus the river has already done much of the coarse grind for you - a nice bonus! Petrified wood can be found in gravel pits and river gravels in Alberta, and my guess is it should show up in the same rivers in Saskatchewan. It isn't colourful like Arizona petrified wood, instead it is mostly shades of brown, probably like what you found at Souris. It can have very interesting banding or other patterns, and the highly silicified pieces are excellent for tumbling. As for how to not be overloaded with what you later find to be leaverite (as in, you should leave 'er 'right where you found it), just be brutal in your assessment of what you want to carry home. Things always look great when seen in bright outdoor light, so be ruthless and only keep the best of the best. Easier said than done, I know. Here's a couple pics -- first one is tumbled Canadian shield rocks, second one is tumbled quartzite. These were collected from the North Saskatchewan river in Alberta. Happy hunting! -Don
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flatlander
starting to shine!
Member since May 2007
Posts: 27
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Post by flatlander on Nov 19, 2007 19:40:19 GMT -5
Thank you both for your advice. One of the first loads we tried was one of granite river rock, picked the ones that were almost perfectly round already, they definitely took a shine, nice, in a curling rock sort of way, but not the striking effect of the translucence, and color I see on this site. My son was doing a unit at school on rocks, so my wife took our tumbler there through the various stages to polish some of the Souris Manitoba rocks. These rocks from Souris are hard as h@##, the outside has defintely been worn by glacier, or water movement but they have sort of potato eye indentations and irregularities that look to be from when they were formed. I hate to break them, so I bought some diamond blades from princess auto, put one in my angle grinder, and had a go at some to try to pre round the inside corners and crevaces so that they might polish better, or take less time to rough tumble. The diamond did cut them, but mostly chipped away, which accomplished what I wanted anyway. They turned out fabulous, but alas shiny rocks and 10 year olds, (none came home). The one rock I cut in half definitely has mossy inclusions. I have tried to polish some of the white quartz you mentioned, my daughter used collect what she called crystal clears. They definitely shine but just shiny white rocks. When I bought the tumbler from the rock shed, I bought some of the brazilian blue agate which turned out good. defintely a learning curve when it comes to tumbling rocks of different hardness. . But I am getting carried away, back to the topic. I was hoping that maybe the agates in Montana and South Dakota, might have had their origins further north, instead of the other way around. South Saskatchewan river is very sandy as it winds through Saskatoon, but further west near Borden there are lots of gravel pits along the river, so maybe I'll check them out. There used to be a rock shop here, Bakke's I think it was, maybe I'll see if he still lives around here, he might have some spots to look. It would be interesting to see what the bedrock looks like around that mine in Thunder Bay, that should be in the Sheild, just like north of La Ronge. Thanks again Doug
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flatlander
starting to shine!
Member since May 2007
Posts: 27
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Post by flatlander on Nov 20, 2007 9:01:04 GMT -5
Well last night I went throught the phone book, and there were only 5 Bakke's, the last one was Eldon, the owner of Bakke's rock shop for 29 years in Saskatoon. I understand what Rallyrocks was saying about the basement now, and both of your explanations about the till. There are probably lots of agates in Saskatchewan, they just are buried under all that till. He did tell me of a place where he said there was like a petrified forest not too far from here, and of a guy who used to find agates in the river and gravel pits around North Battleford, so some short trips, but his favorite locations were in Montana. He mentioned that the kimberlite pipes that spawned our diamond mines were found by a couple of rockhounds who brought some rock in to be identified in the 60's. While I am searching around I remember reading about an old prospector, actually a family, who has staked most of the gold mines around La Ronge, maybe I will look him up, maybe he found some agates while he was looking for gold. Thanks again Doug By the way Don we get up to Calgary from time to time, and for a family ski trip during spring break, if you are interested I can pack along some of the Souris rocks for you.
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flatlander
starting to shine!
Member since May 2007
Posts: 27
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Post by flatlander on Nov 20, 2007 11:16:47 GMT -5
The trip to La Ronge would be an expedition, whereas the one to Montana, likely the same distance from here would be like a nice hike, toss in some shopping in the U.S. now that our dollar is up, and I know whick one my wife will pick. Too bad nothing real close here. I am going to post some photos of the Souris rock, maybe someone can tell me if it is what I think it is. Regards, Doug
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Dec 16, 2007 16:45:19 GMT -5
1) Try to find a local club, even if you have to drive an hour or more it would be worth it and you will be amazed at how much you will learn. Local museums, and universities with earth science programs can be a major help as well.
2) When collecting, bring a chipping hammer, eg. an Estwing with the flat blade, not the pointed, this will tell you the hardness and porosity of a rock with a quick bit of chipping. A spray bottle is another good idea, or collect in or after a rain or a flood, and keep an eye out for new gravel bars forming. I'd imagine that colorful jaspers and some modest banded agates are going to be the main things of interest in your area; petrified wood would be well worth looking for.
3) Look for a book by Ann Sabina, I know she's covered Sudbury to Winnipeg and I'm pretty sure her series, "Rocks and Minerals for the Collector" extends all the way west. The Geological Survey of Canada publishes them, easily found online, pretty much anything worth collecting will be covered.
Hope this helps!
SirRoxalot
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