Justinian II, first reign, 685-695. (Billon, 10 mm, 0.52 g, 1 h), struck on flans made by cutting sheet metal rather than by casting or overstriking earlier coins, Rome. Facing bust of Justinian II. Rev. XXX; below, in exergue, ROm. DOC 69. MIB 77. SB 1309. Very rare and unusual. Rough green patina as found. Nearly extremely fine.
From the Sergius & Cædwalla Collection.
The best discussion of these unusual Byzantine issues can be found in the introduction to DOC II (p. 50), which explains their attribution and their function. The rarity of these coins is probably best explained by their tiny size, and their low silver content: surviving pieces simply would not be seen by modern searchers, while others would simply have disintegrated over time.