The 12th Century Trachea & Tetartera.
The monetary reforms of Alexius I led to vast issues during the 12th century of petty coinage in the form of billon trachea and billon and bronze tetartera. While the trachea are mostly reasonably straightforward from a numismatic point of view, the tetartera present more than a few difficulties.
To start with it is not always obvious where the different tetartera were minted. But more particularly, the weights of some of the tetartera issues vary to such a degree that it is not
always clear how they relate to each other, and for that matter to the trachea, with the result that it in some cases it is not immediately obvious whether some types should be rated as tetartera or half-tetartera
(or even some other value).
I am not going to attempt to resolve these problems in this note, but rather my aim is simply to provide a convenient summary of the various types of trachea and tetartera which readers can
use as a basis for assessing the analyses of the tetartera that can be found in the standard publications on these types.
This is done in the accompanying tables, which list the various types of both trachea and tetartera by Sear number, together with the average weights of the types. The latter are derived
from two main sources – firstly, the market, i.e. the weights quoted in auctions or other on-line sales, as revealed by acsearch for example, and secondly, the weights listed in DOC IV, the mean values of which are
shown in square brackets in the tables. (For the commoner types the standard error in the mean weight is typically c.0.1 gm, but for the scarcer types the uncertainty is considerably larger).
For completeness the tables include a number of imitative types, dating mostly from the 13th century, which can easily be confused with their official models. These are shown in italics in
One point is worth making at this point. Rather oddly, although writers like Hendy and Metcalf discuss the problems of the trachea and tetartera in considerable detail, they never seem to
consider one fairly basic question, namely, the weight standard for these types.
Looking at the tables below it would seem that the mean weight of most trachea, and of many of the tetartera, was c.3.9 gm. This suggests that the weight standard for these types at
least was 1/7 ounce, i.e, the weight of the later republican and early imperial denarius. However, it also clear that not all the tetartera conform to this standard, and just how these exceptional types fit into the
monetary system is a problem yet to be solved.