The Pest Posted April 17, 2023 Share Posted April 17, 2023 While chasing a drifty target.... (that turned out to be a piece of a rusty nail)... This small rock popped out as I was tossing dirt... I thought it was my target at first... but the detector didn't register anything... it's not magnetic (pictured is a hard drive magnet that I keep on my shovel)... It's fairly heavy... About as heavy as a #8 lead sinker... It's not slag... (I've dug enough of that over the years)... It looks like there is paint on one side... but It's the actual coloring of this rock...The one rough edge is kinda crystalline... like a freshly broken piece of die cast metal... Its way too heavy to be a piece of driveway gravel... maybe some one will recognize it... 2 Link to comment Share on other sites More sharing options...
jasong Posted April 17, 2023 Share Posted April 17, 2023 Specific gravity would be test #1. Followed by a streak test on unglazed ceramic/porcelain (streak a lead sinker next to it for color comparison), followed by a hardness test which will require scratching it if the first two tests are inconclusive. Specific gravity can be found by putting a small container of water on a scale and zeroing the scale out. Dip your sample on a small string into the water (don't touch the sides or bottom of the container, also air bubbles in the crevices can throw things off). That weight in grams is also conveniently equal to your rock volume in cc's since water is 1 gram/cc and you are weighing water displacement by the sample. Weigh your sample dry now. Divide dry weight by wet weight to get a density in grams/cc. From those tests you should narrow things down, if not ID it. You need a scale that has a precision of at least 0.1 grams, more accuracy is better. 3 Link to comment Share on other sites More sharing options...
Geologyhound Posted April 17, 2023 Share Posted April 17, 2023 Some common things you might have on hand to test hardness: your finger nail (about 2.5), a copper - not zinc but copper - penny (about 3.5), A pocket knife blade (about 5.5), glass (about 5.5 to 7), a steel nail (about 6.5). There is a difference between scratching and pushing hard enough to break the surface of the sample - especially if using a pointed object like a nail. With the exception of your finger nail, try using the rock to scratch each of these items. You can use your finger nail to scratch the rock. As jasong mentioned, definitely use unglazed porcelain for the streak test. Post your results back here and we’ll see what we can do! 2 Link to comment Share on other sites More sharing options...
The Pest Posted April 18, 2023 Author Share Posted April 18, 2023 Ummm.... Howdy Sirs.... I'm a total Noob when it comes to what you're asking for... Do I need to buy a test kit of some sort... I will.... if you tell me what to get... I have pushed on this rock with a small straight screw driver... It's not soft or brittle... I can honestly say It's hard as a rock... when I rubbed the tip of the screw driver back and fourth... Trying to scratch it... It didn't really do anything... the tip of the screw driver is shinny and a bit worn though... any of the jagged edges would easily scratch my desk... where do I get unglazed porcelain??? Link to comment Share on other sites More sharing options...
Geologyhound Posted April 18, 2023 Share Posted April 18, 2023 You can buy hardness test kits, but unless you’re going to do this a lot you can probably make do with items on hand. If you have a broken ceramic pot or a porous ceramic plant pot or a piece of unfinished ceramic tile, any of those would do. You want white ceramic/porcelain. Otherwise you may have trouble discerning the true streak color. The idea here is minerals softer than your streak plate will leave a characteristic streak color. Minerals harder than your streak plate won’t. Either way, it is an important diagnostic indicator. 1 Link to comment Share on other sites More sharing options...
Valens Legacy Posted April 18, 2023 Share Posted April 18, 2023 Steve has several videos that should cover your questions on this, here is the link to watch and learn about how to find out more. 1 Link to comment Share on other sites More sharing options...
338Edgeshooter Posted April 19, 2023 Share Posted April 19, 2023 I have a place near me in Central Point, OR. called the Crater Rock Museum, if the people working cant id it they have geologists that will ID rock/mineral samples, you just fill out a short form and leave the sample with them. Then wait for a call, it can take a few weeks. If you have a rock & gem shop near by stop in and ask them, even if they can not id it they probably know who can. Link to comment Share on other sites More sharing options...
The Pest Posted April 22, 2023 Author Share Posted April 22, 2023 Howdy again Sirs... Thank You for the response... I am watching the Chris Ralph Videos on youtube... It's like being in science class again... ( that was my favorite class)... There is a tile shop just over the state line near me... I'll head over there this week... and see what I can find... I'm assuming "unfinished" means not glassed.... If not I'll stop by my Mom's place and accidentally brutally on purpose knock over a few flower pots... Lol.... just kidding... I'll only knock over one... Chris Ralph 1 Link to comment Share on other sites More sharing options...
Clay Diggins Posted April 22, 2023 Share Posted April 22, 2023 On 4/17/2023 at 12:26 PM, jasong said: Specific gravity would be test #1. Followed by a streak test on unglazed ceramic/porcelain (streak a lead sinker next to it for color comparison), followed by a hardness test which will require scratching it if the first two tests are inconclusive. Specific gravity can be found by putting a small container of water on a scale and zeroing the scale out. Dip your sample on a small string into the water (don't touch the sides or bottom of the container, also air bubbles in the crevices can throw things off). That weight in grams is also conveniently equal to your rock volume in cc's since water is 1 gram/cc and you are weighing water displacement by the sample. Weigh your sample dry now. Divide dry weight by wet weight to get a density in grams/cc. From those tests you should narrow things down, if not ID it. You need a scale that has a precision of at least 0.1 grams, more accuracy is better. These tests only work on minerals. It appears you have a rock? Those tests can tell you some important things about a rock but they can not identify the rock type. If you see actual crystal faces that are consistent in angle from one crystal to another you may have a mineral. I've never seen a mineral like your example but there are a lot of minerals. Since we only have a picture and an estimate of mass I'll have to go with slag. Perhaps a clinker. Is there a rail line nearby? If it is a mineral the Mindat identification search is very useful in my experience. https://www.mindat.org/advanced_search.php 1 Link to comment Share on other sites More sharing options...
GB_Amateur Posted April 22, 2023 Share Posted April 22, 2023 17 minutes ago, The Pest said: There is a tile shop just over the state line near me... I'll head over there this week... and see what I can find... I'm assuming "unfinished" means not glassed.... 'Unglazed' is the word. Most bathroom and floor ceramic tiles are glazed on one side but not the other. Inside surface of a toilet tank is another option, but taking the lid off frequently runs the risk of dropping and breaking it.... The tile shop might have broken pieces they end up tossing, so if that's the case the price should be right. 2 Link to comment Share on other sites More sharing options...
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