I really have been thinking about stepping up my game and acquiring a fabulous gold coin and I have been aware of mis-attributed gold coins existing in the realm of the bottom feeders for quite sometime. I was able to isolate an example from a very reputable dealer who is willing to make a deal.
The one I selected is a rare issue of Yasovarman of Kannauj. A foreign (Huna) warlord in the power vacuum caused by the death of Harsha in North India . The historical record is scarce and most of the info on Yasovarman comes from 2 main documents. An epic poem written by Vakpati during his lifetime, which claims he was the incarnation of Vishnu and was undefeated and subjected many lands to his rule. He claimed decent from the king Kidarite Hun Kidara and thus called himself Kushan. He allied himself with Tang China to crush the Tibetans. He sought to push art and science forward. Another 13th century manuscript says Yasovarman was was an epic ruler who was defeated by a King in Kashmir but this story reads like fiction. (according to scholars) There is little else to go on here, just that some weird gold coins pop up in the record when almost no others are present. I was doing some research into the type and they are very incosistant with alloy. Some have a gold content of about 30% (9K) most are ~58% (14K) few are (22K). Some are rose gold, alloyed with copper. Some are electrum alloyed with silver. Based on the dimensions color, weight and date its Electrum probably 14-18K not white enough to be white gold. I suspect the coin has a hint of green which would suggest silver alloy. The coin approximately the same diameter and thickness of a early third century Roman Double denarius.
I employed the knowledge of the ancients and my uber sensitive fluid densitometer and an analytic balance in order to extrapolate the density of the coin. The coin has a density of 15.21 g / cm3. I then did a little math based on the densities of the three top coin metals, Gold, Silver and Copper and also applied a Gold alloy triangle chart to compare color to the coin and I with some certainty I was able to determine the mass% of the constituents in this case Gold and Silver. I have the exact numbers on my desk at the office but it was nearly 50:50. 53% Gold 47% Silver. Electrum!!
Now before some other science(ish) person rips my head off, there are certain difficulties in determining purity based on SG. You need a sufficiently dense fluid (I used reagent Type II Water) and your specimen has to free of encrustation, oils and you have to eliminate air trapped between your solid and fluid that can adversely affect your result. So there is a slight margin of error in my calculation. I attempted to mitigate the error by performing my experiment at a constant temperature of 15.56 deg C. / 60 deg F in an inert Argon bag environment as well as performing a thorough acetone wash before hand. Light trace metals also can cause some error in calculation, since I was able to mitigate most causes of error, I consider the error to be minute.
So I correct the scholars and say this coin is electrum not "base" gold.
As far as these coins are concerned I had to get the Rare and probably the most awesome king.
I will not attempt to butcher the complex history of post-Gupta India. So for some nice easy reading check out...
http://en.wikipedia.org/wiki/YashovarmanKidarite Huns
India, Kannauj
Yashosvarman of Kannauj (AD 728-745)
EL Dinar 22 mm x 7.56 grams
Obverse: Formalized Kushan-style king sacrificing left; below arm, Kidara; in left field, Ka.
Reverse: Semi-realistic goddess Ardoksho enthroned facing, holding garland and cornucopiae; in right field, Sri Yasova; in left field, Rma.
Ref: Smith (1906), Indian Museum Calcutta, Vol. I, Part III, p. 268, 1ff and pl. XXVII, 6; MACW 3649 ("Kidarites", 5th C.). Good Very Fine. Rare.
Posted 05/16/2015 9:46 pm
