Tiberius Billon Tetradrachms of Alexandria

Historical Context

Tiberius's Alexandrian billon tetradrachm series begins in his Egyptian regnal year 7, dated 20/21 CE. The introduction of this provincial denomination must be distinguished from his accession in 14 CE. It belongs to the currency of Roman Egypt, separate from his imperial gold aurei and PONTIF MAXIM silver denarii.

The design pairs Tiberius, the reigning Augustus, with the deified Augustus on the reverse. This arrangement presents the living ruler in relation to his imperial predecessor. A reverse portrait of Augustus does not make the issue an Augustan lifetime coin.

Later issues retain the paired-portrait design while changing regnal dates and portrait orientations. The series is documented through year 23, 36/37 CE. Its chronological span should not be read as evidence of uninterrupted annual production or an unchanging alloy standard.

Obverse Iconographic Composition

Tiberius appears as a laureate head. The wreath and surrounding Greek imperial titles identify the living Augustus. Portrait orientation varies: right-facing heads occur on the cited year-7, year-14, and year-21 types, whereas RPC I 5105 shows him facing left in year 23.

The regnal date accompanies his portrait on these types. The position and legibility of individual letters must be checked on the actual die. Portrait direction alone is insufficient for attribution because it must be combined with the date and the reverse portrait.

Obverse Epigraphy and Inscriptions

The obverse reads ΤΙΒΕΡΙΟΣ ΚΑΙΣΑΡ ΣΕΒΑΣΤΟΣ, transliterated Tiberios Kaisar Sebastos and translated "Tiberius Caesar Augustus".

The year sign is conventionally transcribed L and is followed by Greek numerals. Documented examples include L Ζ, year 7 (20/21 CE); L ΙΔ, year 14 (27/28 CE); L ΚΑ, year 21 (34/35 CE); and L ΚΓ, year 23 (36/37 CE).

These are Egyptian regnal dates, not Roman tribunician numerals. A partially preserved numeral should not be completed solely from a broad ruler date or the facing direction of the portrait.

Reverse Iconographic Composition

The reverse shows the radiate head of Divus Augustus, identified explicitly by the divine title in its Greek inscription. This combines portrait and text to distinguish Augustus's commemorative status from that of the reigning Tiberius.

The two heads do not invariably face in the same direction. They both face right on RPC I 5089; Tiberius faces right and Augustus left on RPC I 5090. The year-21 type RPC I 5100 includes a lituus beside Augustus, whose head faces left. The year-23 type RPC I 5105 pairs a left-facing Tiberius with a right-facing Augustus. Orientation and additional symbols are independent attribution criteria.

Reverse Epigraphy and Inscriptions

The reverse inscription is ΘΕΟΣ ΣΕΒΑΣΤΟΣ, transliterated Theos Sebastos and translated "the divine Augustus". It identifies the portrait as the deified imperial predecessor.

The checked types retain this wording despite differences in portrait direction and the presence of the lituus on one variety. Claims for reversed word order or additional inscriptions require their own dated type evidence; they should not be inferred from damaged lettering.

Typology and Documented Variants

Selected verified types illustrate the series:

• RPC I 5089, year 7 (20/21 CE): laureate Tiberius right; radiate Augustus right.
• RPC I 5090, year 14 (27/28 CE): laureate Tiberius right; radiate Augustus left.
• RPC I 5100, year 21 (34/35 CE): laureate Tiberius right; radiate Augustus left with lituus.
• RPC I 5105, year 23 (36/37 CE): laureate Tiberius left; radiate Augustus right.

This selection is not a complete annual inventory. Each date, portrait pairing, and symbol should be checked against its own catalogue record. The official supplement additionally discusses three coins reported as year 11; that report belongs in the attribution problem rather than being silently rejected or promoted to a fully verified emission.

Catalogue measurements describe surviving specimens or defined samples. They do not prove a universal flan weight, a casting procedure, or an organic-acid surface-enrichment process.

Scholarly Debates and Attribution Limitations

The reported year-11 coins require careful treatment. The official RPC supplement notes M. Shahin's publication of three coins assigned to that year, 24/25 CE. That does not authenticate every reading, but it prevents a blanket statement that all such reports are demonstrably misread year-7 or year-14 coins.

Alloy evidence must also be kept at its proper scale. RPC records legacy analytical notes of 31.5% AR for 5089, 40.6% AR for 5090, and 28.7% for 5100. These differing annotations cannot establish a universal 22-26% target, and none is an assay of an otherwise untested coin. A catalogue metal label likewise does not supply fineness.

The publisher identifies Butcher and Ponting's Egypt chapter as pages 606-664 of The Metallurgy of Roman Silver Coinage: From the Reform of Nero to the Reform of Trajan. That bibliographic confirmation does not verify all analytical claims attributed to the chapter. Exact tariffs, fine-silver equivalence with a denarius, bullion provenance, fiscal profits, and reconstructed output require specific analytical or documentary evidence.

References

1. Roman Provincial Coinage Online: Tiberius, year 7. RPC I 5089, type record
2. Kevin Butcher and Matthew Ponting, The Metallurgy of Roman Silver Coinage: From the Reform of Nero to the Reform of Trajan, Chapter 20: Egypt. Egypt, pp. 606-664; DOI 10.1017/CBO9781139225274.024; publisher bibliographic record
3. Roman Provincial Coinage Online: Tiberius, year 14. RPC I 5090, type record
4. Roman Provincial Coinage Online: Tiberius, year 21, lituus reverse. RPC I 5100, type record
5. Roman Provincial Coinage Online: Tiberius, year 23. RPC I 5105, type record
6. Roman Provincial Coinage Consolidated Supplement (1992-2015). Egypt, Tiberius discussion; M. Shahin's three reported year-11 coins