Silver Content of Parthian Drachms

Below are the silver contents of 37 Parthian drachms; the figures ignore the odd one or two percent of gold in some coins, which was probably introduced as an impurity in the silver. Dates are according to Caley (1955):

1) Arsaces I(?) 250-248 BCE 94.6% silver
(There is no certainty that Arsaces ever minted coins; his successors Tiridates I (248/7-210) and Arsaces II (210-191) both used his name on their coinage, and this may well be a mistaken attribution)

2) Mithridates I 171-138 BCE 94.2%
3) Mithridates I                     92.9%
4) Mithridates I                     92.3%
5) Mithridates I                     89.9%
6) Mithridates I                     89.2%
Mean                                     91.7%

7) Phraates II 138-128/127 BCE 70.9%

8) Artabanus II 88-77 BCE 85.4%
9) Artabanus II                  72.8%
Mean                                 79.1%

10) Sinatruces 77-70 BCE 67.9%

11) Phraates III(?) 70-57 BCE 70.9%

12) Orodes I 57-38/37 BCE 75.6%
13) Orodes I                       74.8%
14) Orodes I                       74.4%
15) Orodes I                       74.2%
16) Orodes I                       69.8%
17) Orodes I                       66.8%
18) Orodes I                       65.2%
19) Orodes I                       58.2%
20) Orodes I                       51.0%
21) Orodes I                       47.3%
22) Orodes I                       46.4%
23) Orodes I                       43.1%
24) Orodes I                       41.8%
Mean                                   60.7%

25) Tiridates II(?) 26 BCE 61.1%

26) Orodes II 4.6 CE 79.8%
27) Orodes II            62.2%
Mean                        71.0%

28) Vardanes I 41/42-45 CE 74.3%

29) Gotarzes II 40/41-51 CE 80.5%
30) Gotarzes II                     76.9%
31) Gotarzes II                     75.5%
Mean                                     77.6%

32) Vologases II 77/78-147 CE 73.3%

33) Mithridates IV 130-147 CE 77.0%
34) Mithridates IV                    74.9%
Mean                                        76.0%

35) Vologases IV 191-207/208 CE 77.9%

36) Vologases V 207/208-222 CE 52.1%

37 Artabanus V 213-227 CE 74.6%

Clearly, the finest coins are the very early ones, with some debasement taking place at some point after the reign of Mithridates I. The coins of Orodes I are debased, with the very wide variation possibly pointing to successive debasement, apparently with bronze, through his reign. The coinage subsequently recovers, so this probably points to economic problems during a single reign. As Orodes' reign overlaps with that of Mithridates II (123-88 BCE), whose coins are unfortunately not included in the analysis, it is likely that, during at least part of his reign, he only controlled part of Parthia. His reign ushered in the confused 'Dark Age' of Parthian history, where the exact succession is still unclear.

The subsequent recovery of the coinage indicates that re-minting of coin was not taking place to any great extent. The Roman practice of successive debasements was clearly not followed.