GotAU? 98 Posted June 10, 2020 Share Posted June 10, 2020 (edited) I was thinking it was tungsten (Wolframite) at first because it feels very heavy. But then I saw the low specific gravity and it’s just too light to be tungsten, it’s more in line with magnetite. And ideas? Streak: dark brown Weight: 87.9g Volume: 16ml Specific Gravity: 5.5g/cc Hardness: unk (will update) Highly attracted to magnets And the weird part is a GPX 4500 will not sense it, and a Gold Monster 1000 will jusy barely pick it up. Edited June 10, 2020 by GotAU? Quote Link to post Share on other sites
Morlock 1,678 Posted June 10, 2020 Share Posted June 10, 2020 Given the magnetic properties, It could be an impure specimen of hematite and magnetite. Sometimes you see a mixture of two minerals within the same specimen, esp iron minerals. The dark gray or black streak of magnetite and the reddish brown streak of hematite would produce a brown streak. That's just my guess. It's hard to know without having the specimen in hand. 1 Quote Link to post Share on other sites
GotAU? 98 Posted June 10, 2020 Author Share Posted June 10, 2020 3 hours ago, Morlock said: Given the magnetic properties, It could be an impure specimen of hematite and magnetite. Sometimes you see a mixture of two minerals within the same specimen, esp iron minerals. The dark gray or black streak of magnetite and the reddish brown streak of hematite would produce a brown streak. That's just my guess. It's hard to know without having the specimen in hand. It also has very shiny metallic surfaces on it (the overexposed parts in the photo), like dark chrome or overheated dark blue stainless. Quote Link to post Share on other sites
Bedrock Bob 3,996 Posted June 10, 2020 Share Posted June 10, 2020 A brown streak is a red hue. That indicates hematite. The shiny faces are probably magnetite. Or one of several similar variations. I think it is iron in a couple forms. Morlock nailed it IMHO. 1 Quote Link to post Share on other sites
Morlock 1,678 Posted June 10, 2020 Share Posted June 10, 2020 34 minutes ago, GotAU? said: It also has very shiny metallic surfaces on it (the overexposed parts in the photo), like dark chrome or overheated dark blue stainless. Another possibility is maghemite. 1 Quote Link to post Share on other sites
GotAU? 98 Posted June 10, 2020 Author Share Posted June 10, 2020 8 minutes ago, Morlock said: Another possibility is maghemite. With all the iron in it, I was surprised that the detectors can’t pick it up, have you noticed this as well? I found galena does this also. Quote Link to post Share on other sites
Morlock 1,678 Posted June 10, 2020 Share Posted June 10, 2020 28 minutes ago, Morlock said: Another possibility is maghemite. https://en.wikipedia.org/wiki/Maghemite 1 Quote Link to post Share on other sites
Bedrock Bob 3,996 Posted June 10, 2020 Share Posted June 10, 2020 18 minutes ago, GotAU? said: With all the iron in it, I was surprised that the detectors can’t pick it up, have you noticed this as well? I found galena does this also. Mineral iron is generally invisible to a PI. And it gives a different signal on most VLF machines. 1 Quote Link to post Share on other sites
Morlock 1,678 Posted June 10, 2020 Share Posted June 10, 2020 23 minutes ago, Bedrock Bob said: Mineral iron is generally invisible to a PI. And it gives a different signal on most VLF machines. Depends on the type of detector, size of specimen, composition, etc. I ran my gold bug 2 over a piece of pyrite which is iron sulphide and it completely ignored it. I ran the same detector over a similar sized piece of galena which is lead sulphide and it sounded off. They all react differently depending on a few factors. 1 Quote Link to post Share on other sites
GotAU? 98 Posted June 10, 2020 Author Share Posted June 10, 2020 48 minutes ago, Bedrock Bob said: Mineral iron is generally invisible to a PI. And it gives a different signal on most VLF machines. 17 minutes ago, Morlock said: Depends on the type of detector, size of specimen, composition, etc. I ran my gold bug 2 over a piece of pyrite which is iron sulphide and it completely ignored it. I ran the same detector over a similar sized piece of galena which is lead sulphide and it sounded off. They all react differently depending on a few factors. Those are interesting results. I have a galena crystal specimen that we purchased from a rock shop and another one I found and neither my Gold Monster nor GPX4500 can detect them. As for this maghemitite (or?), only the GM can detect it, but very weakly and very close to the coil. Besides the measurements I tried, specific weight, hardness (still waiting to do that), color streak and magnetism/attractiveness, are there other tests doable at home for Identifying it? Quote Link to post Share on other sites
Morlock 1,678 Posted June 11, 2020 Share Posted June 11, 2020 17 hours ago, GotAU? said: Those are interesting results. I have a galena crystal specimen that we purchased from a rock shop and another one I found a Besides the measurements I tried, specific weight, hardness (still waiting to do that), color streak and magnetism/attractiveness, are there other tests doable at home for Identifying it? Unless you want to spend hundreds on a xrf gun, you've covered everything. Quote Link to post Share on other sites
GotAU? 98 Posted June 11, 2020 Author Share Posted June 11, 2020 (edited) 8 hours ago, Morlock said: Unless you want to spend hundreds on a xrf gun, you've covered everything. Googled it. Forget the fart gun, I want one of those XRF guns now! Thanks for your replies though, it was helpful information. Edited June 11, 2020 by GotAU? 1 Quote Link to post Share on other sites
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