To be fake or not Vespasian Denarius RIC III 942

[Christiano]

I am a novel coin collector and I have jus won on Ebay an auction.
The coin seems to have a low weight 2.88gr and the quality of silver is low (it seems containing lead) and extremely dark toned. However it comes from an highly trusted ebay seller. I have also analyzed under the microscope and the coin seems good at my novice`s eye. I would be extremely grateful for your comments.

[commodus]

Looks fine from the pictures and there's nothing questionable about the weight. What do you mean it seems to contain lead?
Is it the feel of the coin, perhaps? Quite honestly, I see no reason to suspect it based on the images you've posted.

[gavignano]

Looks ok.
Silver coins can occasionally have very dark toning.

[Christiano]

Thank all of you for your comments.
My concern stems from the quality of the metal. The lead contamination is easily traceable looking at the yellow reflexes of the concretions under the microscope. Also copper is present along, due to the green. It seems that at the end of the Vespasian reign there was a shortage of silver. However, I have checked the weight of the same pieces sold in the auctions and they were always in the range 3.16-3.28 gr. Therefore, this coin seems different from the average in weight and with more contamination in the metal.
Anyway, the fact that your expert eyes do not find nothing strange make me less nervous.

[Rich Beale]

The colour of the concretions is not necessarily an indicator of the metal content of the coin, since they most often stem from the environmental conditions in which the coin lay; the mineral content of the surrounding soil and the decay of any  other nearby objects are the principal factors in determining the type and nature of the deposits on the coin surface.

That said, Roman silver does often contain significant impurities, and lead is often among these. However, since lead is more dense than silver, significant amounts of lead woul make the coin heavier rather than lighter than the average.

Stylistically there is nothing wrong with your coin, and indeed it is a very attractive specimen of the type. I would not be concerned about the weight or the deposits.

[commodus]

The weight is fine. Check more sourceas and you'll see it is within range. On the lighter side, perhaps, but nothing to be suspicious of.
To give physical strength to the coinage, silver is always alloyed with other metals, particularly with copper (the same holds true with gold coinage). A bit of lead could certainly have found its way in there with the copper. Compared with modern coinage, ancient alloys were neither precise nor pure. This is nothing to be concerned about.

[PeterD]

Silver is usually found in the ground mixed with other metals, particularly lead and copper.

Smelting of ores to extract the silver left impurities behind. Silver could be further refined in a process called cupellation but that was a slow process that could only be done in small quantities (in a "cup"). That also involved the use of lead. I would imagine for coins the basic impure metal would have been used.

[Torsten]

a very nice piece which is not very common.

[Robert_Brenchley]

Silver is often found as an impurity in lead, as they occur together. They're very closely related chemically, and molten lead dissolves silver. Did the stuff that looked like lead have a whitish oxidised surface? If not, it may well be toning.

[Christiano]

Great!
Thank you so much from what I learned from you.
You faded my doubts in a very convincing way. This is truly a big forum plenty of skilled people.