They are magnetic and do not leave a residue when scraped against an unglazed bathroom tile (a test to differentiate from earthly hematite and magnetite which do leave a residue.)
There are definite signs of fusion crust on the back of the right hand object in the first image. Unfortunately it requires a macro image which is beyond the scope of my camera or I would have to cross section a sample.
Incidentally these samples are quite heavy for their sizes.
I'm thinking of testing the samples using X-ray spectroscopy.
I believe a high nickel content is a property for iron meteorites.
You can send them to Sydney and have them tested. But it's rarely worth the cost of sending it down, unless it's of significant size.
In which case one should photograph the suspect in it's original location and use a sat nav to get accurate coordinates.
I highly recommend the book "Field Guide to Meteors and Meteorites" by O. Richard Norton and Lawrence A. Chitwood.
If they're big enough, cut one in half length ways. If you see a cross hatched pattern of crystal growth (Widmanstatten Lines) after etching and polishing, then it's definitely a meteorite. But some don't have the pattern....it's due to nickel content in the rock.
It's actually very hard to tell what they are from those piccies. Where did you find them?? If they're terrestrial, they're most likely (from their colour and the weight you described) a nickel-iron ore, or an ore of some other mineral of that colour such as chromite, chromite-nickel, chromite-vanadite and/or one of the rare earths.
You can send them to Sydney and have them tested. But it's rarely worth the cost of sending it down, unless it's of significant size.
In which case one should photograph the suspect in it's original location and use a sat nav to get accurate coordinates.
I highly recommend the book "Field Guide to Meteors and Meteorites" by O. Richard Norton and Lawrence A. Chitwood.
Thanks Jeanette.
It's interesting that the samples were found in two remote locations, each location has been marked using GPS. So it's possible there is more stuff to be discovered.
Fortunately I have connections in Victoria so getting a sample tested for free shouldn't present any problems.
If they're big enough, cut one in half length ways. If you see a cross hatched pattern of crystal growth (Widmanstatten Lines) after etching and polishing, then it's definitely a meteorite. But some don't have the pattern....it's due to nickel content in the rock.
It's actually very hard to tell what they are from those piccies. Where did you find them?? If they're terrestrial, they're most likely (from their colour and the weight you described) a nickel-iron ore, or an ore of some other mineral of that colour such as chromite, chromite-nickel, chromite-vanadite and/or one of the rare earths.
Hi Carl,
There quite small. The object in the second image is approximately 30mm X 30mm X 10mm thick and weighs 58g.
They were found in a dry creek bed at a depth of about 75mm - 100mm below a sandy sediment. Found at two locations about 30 metres apart.
It would be great if they turn out to be meteorite fragments, but you want to hope that they're ore samples from some of the minerals I mentioned...especially any one of the rare earths. If they are, go back to where you found them and do a stream sediment sampling survey and try and trace where they come from. Then form a mining company with someone and take a claim out on the area. Rare earths are a literal gold mine and if it's a large enough deposit you'll make squillions!!!!.
Just had a look at a map of the area, the gully is a boundary between a Historical Park and a National Park!
So much for the potential of mining.....
Regards
Steven
Never stopped them before
If it's worth heaps of money, all the national park or historical monument legislation in the world won't matter jack. If they think they can turn a tidy profit from it and it's in the national interest, they'll mine it.
A rare earth mine, I can assure you, would be in the national interest. But it would all depend on how big the blithering idiots in Canberra were.
Would it be worth starting by checking their density (or sg as a geologist would say). You have the weight and getting the volume is easy. Even if you don't have a measuring cylinder handy you can't determine the volume of water displaced by weight difference. Just catch the overflow in a pre-weighed dish. The density of the water will be <1 but not by much.
I've often wondered what acid is used to etch the Widmanstatten lines.
Possibly nital etching which is nitric acid + alcohol (methanol or ethanol) although I don't think this is advisable if Nickel is involved. Alternatively it could be Picric acid and alcohol.
Nice stuff Picric acid, it's explosive when dry.
A metallurgist I knew blew himself up using Picric acid.
Would it be worth starting by checking their density (or sg as a geologist would say). You have the weight and getting the volume is easy. Even if you don't have a measuring cylinder handy you can't determine the volume of water displaced by weight difference. Just catch the overflow in a pre-weighed dish. The density of the water will be <1 but not by much.
Measured SG is 7.2.
Iron meteorites are in the range 7.0-8.0.
I've often wondered what acid is used to etch the Widmanstatten lines.
I used Nitric acid to etch mine (years ago) and, providing you use standard safety procedures, it is very safe. I was led to believe that Widmanstaten Lines can only be found in Meteorites due to a cooling of the original molten material at a rate of 1 degree per million years. Not my area of expertise so I can't swear to it.
I've often wondered what acid is used to etch the Widmanstatten lines.
A geologist just told me they are etched with fairly conc nitric. He wasn't sure off hand whether it is neat (ie straight from the winchester) or slightly diluted.
The one we have in a display here was also washed multiple times in clean water, dried in a vacuum oven for some hours and then coated with clear lacquer to protect it from rusting. The Widmanstatten pattern is very obvious.
