Hello friends. I have seen someone is trying to sell a coin described as Mysia Kyzikos Electrum. It weighs 5.8gm and measures 19mm. It looks very similar to the coin picture attached but I can only find two weights for this type 10.7gm and 8.1gm. So is it not possible to have a weight of 5.8gm or were similar designed coins of a lesser weight also made?
These coins come in many different weights and sizes. And there is no way to tell if it is fake or real with a picture of a semi similar coin... Pic from "100 Greatest Ancient coins"
The 10 gram coin would be a stater, or double siglos. I don't know whether the confronted bull-lion type was struck in smaller denominations. In the 6th century BC, the mint at Kyzikos struck coins as small as 1/12 of a stater. I don't have a reference for these coins, but the point is, you have to know the denomination you're dealing with in order to assess the weight properly.
The coin in the picture is a Lydian coin. Unfortunately, there is no coin printed by the Kyzikos mint in the legend and according to the weight you gave.How do I know? I am currently living 20 km away from the old city of Kyzikos. Sorry for my english. I use google translate.