Au Seeker 3,137 Posted December 18, 2013 Share Posted December 18, 2013 Cool thanks for the response.. I agree with you. I'm not sure what you mean by streak testing though. I can get my hands on a piece of slate tho got all kinds around here. A streak test is where you rub the mineral/rock on a test plate, the best material for a test plate would be unglazed ceramic, it will work for almost all specimen because of it's hardness, I don't think slate will work well in all cases because a mineral maybe harder than the slate, and since color streaks varied from black to white and all color in between sometimes you will need a white test plate and other times you will need a black plate and observe the color left on the test plate, which is many cases is not the color of the specimen being tested. The streak color for Opal is white, irregardless of the color of the opal. http://www.minerals.net/mineral/opal.aspx The streak color for agate unfortunately is also white, so a streak test will not help in this instance, but you have learned something about how to determine what a mineral is for future reference. http://www.minerals.net/mineral/agate.aspx There other characteristics of all minerals that may help, they are hardness, specific gravity, cleavage, fracture, color, etc., check out the links for Opal and Agate, and then research/search the internet for how to determine the above mentioned and other characteristics, in this case the main difference in Opal and Agate is the hardness, they're close on the hardness but an accurate test should help, Agate is 7 on Mohs hardness scale and Opal is 4.5 to 6.5, most all of the other characteristics are much the same, so research how to determine the hardness of your specimen and you may have your answer. I could also provide you with the How-to on the hardness, but I think you trying to find it on the internet yourself will greatly help you in the future with IDing minerals you find, I will check out this topic as time goes on in case you still need help. Quote Link to post Share on other sites
j! 6 Posted December 18, 2013 Share Posted December 18, 2013 Buzzy,two of the most common ways to get a good idea of what you've dug up are hardness and streaking. The hardness is the mohs scale -- and chalcedony is harder than opal. This is generally called a 'scratch test'. Now, when I was a rock pup we were always told to use a slate tile, but in looking up streak testing online it appears you're supposed to use an un-glazed porcelain tile. Drag the rock across and the color of the streak will indicate the type of mineral. You can find color tables for a streak test online or any reputable reference book on minerals! Quote Link to post Share on other sites
j! 6 Posted December 18, 2013 Share Posted December 18, 2013 LOL -- I had to run out halfway through writing that this morning and left it open on the PC. Just got back, finished it and posted it and I see AU Seeker has given a more complete answer! Quote Link to post Share on other sites
Au Seeker 3,137 Posted December 18, 2013 Share Posted December 18, 2013 LOL -- I had to run out halfway through writing that this morning and left it open on the PC. Just got back, finished it and posted it and I see AU Seeker has given a more complete answer!J, we make a great tag team!! Quote Link to post Share on other sites
Buzzy84 0 Posted December 19, 2013 Author Share Posted December 19, 2013 A streak test is where you rub the mineral/rock on a test plate, the best material for a test plate would be unglazed ceramic, it will work for almost all specimen because of it's hardness, I don't think slate will work well in all cases because a mineral maybe harder than the slate, and since color streaks varied from black to white and all color in between sometimes you will need a white test plate and other times you will need a black plate and observe the color left on the test plate, which is many cases is not the color of the specimen being tested. The streak color for Opal is white, irregardless of the color of the opal. http://www.minerals.net/mineral/opal.aspx The streak color for agate unfortunately is also white, so a streak test will not help in this instance, but you have learned something about how to determine what a mineral is for future reference. http://www.minerals.net/mineral/agate.aspx There other characteristics of all minerals that may help, they are hardness, specific gravity, cleavage, fracture, color, etc., check out the links for Opal and Agate, and then research/search the internet for how to determine the above mentioned and other characteristics, in this case the main difference in Opal and Agate is the hardness, they're close on the hardness but an accurate test should help, Agate is 7 on Mohs hardness scale and Opal is 4.5 to 6.5, most all of the other characteristics are much the same, so research how to determine the hardness of your specimen and you may have your answer. I could also provide you with the How-to on the hardness, but I think you trying to find it on the internet yourself will greatly help you in the future with IDing minerals you find, I will check out this topic as time goes on in case you still need help. so it sounds like i should maybe break this rock up to do that kind of test? If so what would be the best way to do that without totally screwing the thing up? Quote Link to post Share on other sites
Buzzy84 0 Posted December 19, 2013 Author Share Posted December 19, 2013 LOL -- I had to run out halfway through writing that this morning and left it open on the PC. Just got back, finished it and posted it and I see AU Seeker has given a more complete answer!lol Thanks j I looked it up too after i read your comment. Quote Link to post Share on other sites
Haderly 99 Posted December 19, 2013 Share Posted December 19, 2013 I don't think you should go busting it up to do a streak test. In this instance you are likely dealing with agate, jasper, chert or flint so all results are going to be very similar. If you want to do it just for the fun and learning experience then go for it. You can always use the inside of a toilet tank lid for a streak test. Rub the lid against the rock so you don't have to lift the rock and possibly drop it on the tank lid. If it is petrified wood from Arizona then it would be agate not opal. I have not seen opal replaced wood in these colors even though it is possible but looking at the pictures I would say it is very unlikely. Opal would have a very glassy conical fracture so it will be very easy to rule out if you don't see it. Quote Link to post Share on other sites
Au Seeker 3,137 Posted December 19, 2013 Share Posted December 19, 2013 You don't have to break up the specimen to do most of the tests, you would have to break off a tiny piece to determine the fracture, but for all others there's no need to break it at all. Quote Link to post Share on other sites
Buzzy84 0 Posted December 19, 2013 Author Share Posted December 19, 2013 Ya i don't know. Maybe instead i should of asked what type of shop i could bring this to, to identify in person. I'm confused lol I did learn some things tho so thank you all!. I'm not gonna break it up but might try the toilet lid idea next time i see the rock.But ya who normally identifies something like this a gem and gold shop? Quote Link to post Share on other sites
j! 6 Posted December 19, 2013 Share Posted December 19, 2013 (edited) Look for a local rock hounding group. They're the most likely to have someone that can give you a hands on identification.Maine is a good place for gemstone hunting. Besides being an apparently good source for finding out of place petrified wood, you have a lot of pegmatite formations throughout the state - which is where you can find tourmaline, beryls and other gemstones! Google is your friend! Edited December 19, 2013 by j! Quote Link to post Share on other sites
Haderly 99 Posted December 19, 2013 Share Posted December 19, 2013 http://digmainegems.com/index.htm is close to you and should have someone to help you out. If they cannot help you then this place should http://www.facebook.com/pages/Maine-Lapidary-Supply/153371768028504 Quote Link to post Share on other sites
Buzzy84 0 Posted December 19, 2013 Author Share Posted December 19, 2013 Look for a local rock hounding group. They're the most likely to have someone that can give you a hands on identification.Maine is a good place for gemstone hunting. Besides being an apparently good source for finding out of place petrified wood, you have a lot of pegmatite formations throughout the state - which is where you can find tourmaline, beryls and other gemstones! Google is your friend!Ok i'll check into that.. Oh yes we have Alot of tourmaline around here and plenty more to be found im sure! I would like to get into gemstone hunting and also gold panning as we have alot of that too that has yet to be found and lots of other gems and geodes. It's a wonderful state thats for sure! Quote Link to post Share on other sites
Buzzy84 0 Posted December 19, 2013 Author Share Posted December 19, 2013 http://digmainegems.com/index.htm is close to you and should have someone to help you out. If they cannot help you then this place should http://www.facebook.com/pages/Maine-Lapidary-Supply/153371768028504 Thanks i'll check them out next summer if i cant find another place seems they're only open from may til october but i'll try to email them.. And that facebook page seems to be dead since 2011 lol Quote Link to post Share on other sites
JohnH 1 Posted December 20, 2013 Share Posted December 20, 2013 I lean pretty hard for opalized wood. Quote Link to post Share on other sites
Buzzy84 0 Posted December 24, 2013 Author Share Posted December 24, 2013 Well everyone thanks for the input. I am not gonna be able to get pics for a while now cuz its covered in snow and my friend is beyond lazy. But I think i have a great starting point now thanks to everyone that posted! Next year if i get it tested or some better pics i'll start up a new thread. Quote Link to post Share on other sites
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