Tibetan Ga-den Tangkas: Mintage and Purity

[gaden]

Mintage
I am looking for a key source on the total mintage of Tibetan Ga-den Tangkas.
Both Semans 1980s (Info Sheet 11) and Rhodes 1983 (ONS Occasional Paper No. 17) cite "Kempf, Fred, 1969, (A Primary Report on) Native Tibetan Coins, Seattle, Washington" as their source for tibetan mintage. Unfortunately, I cannot find the full article anywhere.

• Semans 1980s says: "The low-cost availability of this coin from India today attests both to its prodigious original mintage and its extensive use in border regions (3 Tangka = 1 Rupee). Kempf estimates an original mintage of 50 million, though even this seems low".
• Rhodes 1983 says (about the H type): "According to a report by Weir dated 6th February 1929, the Tibetans were preparing to issue silver tangkas to "be turned out at a rate of 3'000 tangkas an hour by machinery worked by electricity", [...] although the rarity of this class seems to imply that production cannot have lasted more than a few days if they really were struck at the rate of 3'000 a day [sic]".

There is clearly a problem in Rhodes 1983 as he first says "3'000 an hour" and then "3'000 a day". It's also unclear what "a few days" means. Assuming he meant 3'000 a day and a few days is 3 days, then total H type coinage is 9'000. Assuming he meant 3'000 an hour and a few days means 9 days, then total H type coinage is 648'000. Assuming frequency of the H type is in the range [0.8%, 1.4%] (Rhodes, Semans, zeno), then that means that total Ga-den tangka coinage was in the range from ~700'000 to ~84'000'000.

Putting together all this information, it looks like total mintage might be in the range 50 million to 80 million.

My question is two-fold:

• Does anyone have a copy of: "Kempf, Fred, 1969, (A Primary Report on) Native Tibetan Coins, Seattle, Washington"
• Does anyone have estimates of Ga-den Tangka total mintage? Do my estimates look accurate?

Purity
Purity estimates seem to differ a lot, and I cannot find any estimates:

• numista quotes Ag .850 (XRF, no source)
• zeno (XRF by Gordian) has data for three coins:
  
  • type F "(xc)": Ag .589-970
  • type F "(xc)": Ag .483
  • type F "(xc)": Ag .938
• Rhodes 1983 says: "[...] Sir Charles Bell was told in 1921 that a standard 2/3rds silver to 1/3rd copper was aimed for which, if it was achieved, would not differ greatly from the fineness of the 19th century issues. On the other hand, the few readings obtained using specific gravity methods, indicate a fineness nearer 40% around 1920 [...]".

Rhodes and Semans even contradict each other. Rhodes 1983 says "[Talking about the period 1922-1925] During this period the Gaden Tangka was known colloquially as Tangka Ghabo ie. white tangka, because of the blanching process to which the coins were subjected before striking in order to hide the poor quality of the silver". Semans says "Throughout its history the Gaden, or Dkar-po, meaning literally "White" Tangka from the color of its high purity silver, remained fairly constant in weight and purity".

Does anyone have more information or sources on the purity of these coins?

[Gusev]

I looked through my entire library of Tibetan coins. Unfortunately, I don't have an article "Kempf, Fred, 1969, (A Primary Report on) Native Tibetan Coins, Seattle, Washington".
Also, I did not find separate studies on the mintage of the Gaden Tangka.
We have little verified source data for making calculations for the minting of these coins.
Your circulation estimate is the first step. It is necessary to look for additional sources.
Since Gaden Tangka coins are still common today, it can be assumed that the original mintage of all types of these coins was in the hundreds of millions. That is, your estimate can be attributed to the lower limit of coinage.
About the contradiction in Rhodes's article. I think it was a simple typo.
Mechanically minting 3000 coins per hour is closer to the truth than 3000 coins per day.

Wolfgang Bertsch in his article "The Second Issue of the 3 Srang Silver Coin of Tibet" provides data on the minting of 3 Srang coins (official government data). The coins were minted for several years in the following circulations:
year 16-9, 1 million
year 16-10, 1.8 million
year 16-11, 2 million
year 16-12, 0.8 million
year 16-20, 0.3 million