I was talking with Victor England from CNG over the weekend in San Francisco and he mentioned something to me that I have never heard before or recall seeing. He said that bronze coins with blue patina come from grave sites. He thought it had something to do with bone calcification or the like. Anyway, sounds kind of cool. Anyone have any blue patina bronzes they'd like to post? I'd like to see what one might look like since I rarely collect or really ever look at bronze coins.
Unless the coin was resting in someone's mouth (as was a custom for the dead back then), I don't know bome calcification would be the cause of this phenomenon you speak of...especially when cremation was so popular. Come to think of it, a coin in a corpse's mouth might not fare well the cremation process. And in the late Empire period, I doubt Christians would be buried with grave goods as there is no need for post-mortem wealth in Christian theology.
I hadn't heard that bit of lore before. As for calcium being the cause, I assume he meant calcium enrichment of the soil as the bones break down. It seems like it would take a mass grave rather than just a person or two. I have a few bluish-green coins from Pontos. This one is the bluest. The condition isn't great but it is attractive nonetheless. I haven't shown it on CoinTalk before. The images aren't color-adjusted nor is the lighting or contrast fiddled with. PONTOS, Amisos Circa 100-85 BCE. Æ (whoops, I haven't recorded the size and weight. It's ~27 mm or so) Obv: Head of Zeus right, wearing laurel wreath Rev: AMI-SOU, eagle standing left, head right, wings spread, on thunderbolt; monogram to left Ref: RG 15; SNG BM Black Sea 1145-6; SNG Stancomb 675; SNG Copenhagen 132
Another Pontos coin with some blue, including some areas of a darker lapis lazuli-like blue: A few of my Pontos bronzes have this blue patina. I assumed it had something to do with the alloy.
...and another blue coin, also from Pontos. This was in a local jewelry store, far FAR away from wherever it was found. While I loved the incredibly colorful thick patina, I wanted to see if it had good reverse details. It did, so removing the colorful patina was worth it. Before (It reminds me of black light posters. Crank up the Floyd! ) After: Note: those heavy scratches were from flan preparation, not from my cleaning. All I did was soak it in a few changes of vinegar, with a few gentle rubs of a cotton-tipped swab.
Truly blue patinas are rare in my experience, but I can't contribute anything of substance to the chemical/geological discussion. Here's a coin of Syracuse with a blue patina that makes Pegasos look like he's flying through the sky...
Bluest I have is Commodus, 2 assaria, Dionysopolis, Phrygia. The B denomination mark is reversed and makes it look like it doubles as a bow for Herakles.
Ummm, maybe my sweet example is an outlier? ... it's not from that Pontos era, but oh my ... => this baby is the sweetest colour "ever" ... it's a very cool coin (pretty rare too, which is always nice, right?)
This worn Ptolemaic coin has a blue-green patina. There was a small hoard of these disbursed into the market a year or two ago, all fairly worn with varying ranges of blue-green mineral patina like this.
I have no blue patinas, but the few I have seen are really cool. But part of me would think it could be bronze disease and ignore it goes for some else to buy. I don't like to chance it.
ahaha ... I'm fairly sure that the blue is merely a wee bit o' copper in the mix (showing its blue hue) ... blue bronze disease (dude, what happened to you and your blankie-coin that you're so rattled by bronze disease?) man, I like you (you're kinda like the super-over-cautious bronze disease guy!!) =>once bitten (never bitten again!!) cheers, Mat (I'm hoping that you're having a merry holidays, my chick-coin collecting friend)
here's a blue patina i produced by accident. this was an uncleaned lot coin, after i cleaned it up i gave it a bake in the oven to dry. when it went in it was your usual "LRB green", when it came out it looked like this... i brushed off the loose stuff and it looked like this... @Ancientnoob explained the process to me i think, but i believe it involved the dehydration of a copper compound.
Interesting... I've never read about blue grave patina either. It doesn't cover all of the coin, but there's some interesting blue stuff going on on this follis of Constantius Chlorus. The seller notes that is from a hoard found in France - "Marchais (Aisne)". I haven't seen any other coins from this hoard, but I assume the ground conditions contributed to the coin's look.
I read somewhere that the Romans believed burying the body was uncivilized. Generally, Romans cremated the body and kept the burial urn in crypts. Anyway, I doubt the fire would have been good for any coins left with the body as payment for Cheron's ferryman. Me thinks it all depends on the ground minerals where the coin laid for a couple thousand years.
Here are two with bluish green deposits, maybe buried next to the graveyard Severus Alexander AE Sestertius. 232 AD. IMP ALEXANDER PIVS AVG, laureate, draped and cuirassed bust right / MARS VLTOR S-C, Mars walking right, holding spear and shield. RIC 635d; Cohen 169, BMC 843. 25mm 6.3g Constantine VII Porphyrogenitus, with Zoe. 913-959. Æ Follis. Constantinople mint. Struck 914-919. Crowned half-length figures of Constantine, wearing loros, and Zoe, wearing chlamys, holding patriarchal cross between / + COҺS / TAҺTIҺO’ / CЄ ZOH ЬA / SILIS RO / MEOҺ in five lines. DOC 22; SB 1758.