Joined: Wed Jan 14, 2015 3:52 pm Posts: 576 Location: N Dakota
I dug into last years find of Montana sapphires. Trying to decide which ones to send in for heat treatment. Lots of stones from 4 to 7mm and a large flat disc. This got me in the prospecting mood again, so I dug into the archives on Montana sapphires. Several areas hold them although they are a bit separated from each other. The gravel bars on the Missouri river east of Helena, rock creek south of Missoula, Yogo gulch in Judith basin county and star sapphires between Dillon and Ennis. Most of these are found in alluvial deposites. Little green stones clog up the sluice box riffles and float the gold out the end. Its only a problem if you are looking for gold! Specific gravity at 3.5 or so I had to flatten out the sluice quite a bit. The rule for gold being 1" drop per foot of box, I ran about an inch for 3 ft. then fed some aluminum slag from the welder through the box and it settled in the first 4 riffles. Perfect unless you try to push too much material, so had to slow way down and spoon feed my baby. I did find some small stuff and some garnet but not what I had hoped for. So I went for the backup plan and hit a pay to mine place near Phillipsburg. That went better, sifted out 150+ cts but it wasnt free. So going to try again, finding an unclaimed creek bottom to work is tough. Not that it isnt open to prospect just that its tough to find the records to verify if its active or abandoned. Why go through all the work? I like to find the stuff im going to work with myself. No chance of it being synthetic or from some other place. And it comes with a story. Im thinking I'll try around rock creek this spring and maybe Helena if I can find access and work the river bars. Anybody else do this stuff?
My wife hails from Montana, so we are fairly often in the area, and I almost always go sapphire hunting. My best luck has been in Philipsburg. My brother in law went with a group that went up into the hills (on horseback, i believe) and dug down to the gravel looking for sapphires. I don't think they were very successful on that trip, though other trips have been quite successful.
Joined: Wed Jan 14, 2015 3:52 pm Posts: 576 Location: N Dakota
I find stuff that's 2mm to 5mm. Clear for the most part or completely clouded with silk. Locals tell me the silky ones clean up the best when heat treated. Color on the other hand is a crap shoot. Generally I find a color like an old coke bottle green or deep lake ice blue. It's just enough to say yes it's this color or that color but I'm told it only gets more intense with heat and could change to any color. I'll take my chances and see what comes out. Got an oz or 2 to play with.
Joined: Tue Jul 02, 2013 9:00 am Posts: 1322 Location: Wylie Texas but in Alaska for a while
Dan, it sounds like you are planning on doing everything from findingthe gem to casting the setting. Have you considered heat treating them as well? There are some threads on it if you search.
If you look for GEM & Gemology fall of 81, they have a nice summary of the different processes.
Joined: Wed Jan 14, 2015 3:52 pm Posts: 576 Location: N Dakota
Well not everything. Lol, done my share of panning for gold and sifting through gravels though. It seems to be a chronic ailment. The only relief I get is to take a trip and dig some dirt. The difference now is I actually plan to do something with my findings besides sell it so I can pay the chiropractor when I'm done! Don't think I'm going to try cooking rocks. The folks up at Gem Mountain in Phillipsburg Mt have that all figured out. Besides I understand they look nice when done but aren't very tasty. I'll stick to steaks.
Joined: Wed Jan 14, 2015 3:52 pm Posts: 576 Location: N Dakota
Ran across a geologist paper on rubys in Wyoming. He seems to have put together a relationship between vermiculite and rubys. Montana has its share of vermiculite, some has asbestos but not all, so maybe I can find the whole report and see if the same conditions exist in Montana. The one thing I didnt see was the quality of the ruby.
Yes there are, fine color and often clean. Unfortunately also often too small to cut. The corundum crystals from the pegmatite are opaque to translucent and fairly large. Just so you do not think I am confused.
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Joined: Wed Jan 14, 2015 3:52 pm Posts: 576 Location: N Dakota
as luck would have it my trip to Phillipsburg MT was cancelled weeks ago. Well the weather turned south, or at least came from the south. Temps here dropped into the 20s and gave us snow. Would have been miserable at elevations above 5000 ft where I had plans of prospecting. So looking to a trip again but this time in August/September. A stop in the Ruby Valley and some time around Phillipsburg. Stay tuned this will happen!
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