Jewelry, Gems, & Minerals/Metal detector find unidentified metal object
QUESTION: I found these two pieces of metal material that show up as 25 c on the metal detector. They are grayish green in color the big one has little circles all over it and is a half circle, it also has a hole in it. The small one is the same color but has some orange color to it. When a magnet is held to it there is no pull what so ever. If you hit them together they kind of have a ring to them..please help or do you know who to ask? Thanks
ANSWER: Hard to tell from the pictures and the description. The best clue is the non-magnetic test. From the looks it could be some kind of pewter. Does the orange color come off when you wash it or is it really stuck to the artifact? The best assessment would be to do a simple density test.
1. Weigh one of the objects and record the mass in grams.
2. Fill a plastic beaker or cup with water. Place the cup with water on the scale and zero out the scale(tare).
3. Tie the same object to a fine string or thread and dangle it into the cup while holding on to it. Make sure the object is completely submersed in water and does not touch the bottom or the sides. The buoyant force should give you a small weight measurement. Record that weight.
4. Use a calculator and divide the dry weight of your sample by the weight recorded when the sample was dangled into the cup with water on the scale. You should get a number somewhere between 5 to 10. That is the specific gravity of the metal in g/cm^3. (If it is real gold or silver, the number will be higher, but will not be over 19... If it is you made a mistake somewhere)
You can now compare this measured density to the density of common metals and metal alloys and it should give you a hint on what this material could be. You could also try to share your results with me and I could help you in another step for your interpretation.
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QUESTION: Wow thanks that helped a lot.
First the bigger one was 140 g dry and 15 g wet weight for a 9.3 result
The little one is 18g dry and 2gwet weight for a 9 result.
Do you think they are pewter?
Thanks for the quick response you were very helpful.
ANSWER: The density of about 9 - 9.3 could suggest some type of bronze or brass as well, which is about 8.9 g/cm^3. That would also be indicative of your greenish color which is an alteration of the copper within. Medieval pewter is possible, but rarely survives since damaged goods were just remelted. It has a low melting point and contains lots of lead or may also contain copper and bismuth. The density should be higher, around 10 or so.
Here are a few more tests: Does it bend easily? Antique pewter is rather soft and could be deformed, especially if it contains lead. This test is not indicative though, because at later periods they mixed the tin with copper and bismuth, which made it harder. This would also be lighter and not give you a density of 9.3 g/cm^3. Also you could do a semi-destructive test. Does it melt in a candle flame? Antique pewter has a very low melting point. Depending on the metal mixture this melting point is around 220 to 240 C (430 to 464 degrees F). Candle flame temperature is about 1,000 C plus. However, this test would unfortunately destroy part of your specimen :-(
Another possibility. Find a university close to you and get in touch with their mineralogy or materials testing department. They might have an instrument called a X-ray Fluorescent spectrometer (XRF). The test with this instrument is non-destructive, very fast and would give you a qualitative and semi-quantitative measure of the metals present in your artifact. If it contains lead, tin, copper, bismuth it is pewter. If significant amounts of copper are present, then it is more likely brass or bronze. Or if iron shows up then maybe it is something totally different.
Hope this helps and good luck on your research.
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QUESTION: Okay last time I message you. I guess I left out the part that we are military located in Germany. It was found on farmland in plowed up fields with a metal detector. It's is hard but I scratched the edge with a pair of heavy duty scissors and it can be cut with some force. It does not melt under candlelight. They one kind of looks like a eagle head when it has dried out you can see an eye and a nose but it might be my creative mind. Where we live it is possible for it to be midevil of some sorts or early 1800s. On the contrary thanks for you answers and quick responses.
I love being able to imagine what it might be or what it was used for.
Might be from the time period described or even WWII. It is not uncommon to turn up relics from the past in farmers fields within Germany. If you won't mind to share the approximate location of your find (you don't need to be too specific), some possibilities might be construed. In Southwestern & Southern Germany, for example, it is not uncommon to find relics from the Roman time period. But historical finds and archeology are outside my realm of expertise. If you won't mind sharing a private e-mail address, I could forward your request to one of our anthropology and / or history faculty. They might be able to help you a little bit better but most likely will need to see some more detailed pictures and maybe close ups of the item. Let me know. You can e-mail me privately at firstname.lastname@example.org.