The famous Papyrus Graecus Holmiensis has been digitized and is online at the World Digital Library here. Also known as the Stockholm Papyrus, this 4th century CE codex contains recipes for mordanting and dying imitation stones. For example, recipe 101 is as follows:
"Cold Dyeing for Purple which is Done in the True Way"
"Keep this as a secret matter because the purple has an extremely luster. Take scrum of woad from the dyer, and a sufficient portion of foreign askant of about the same weight as the scum – the scum is very light – and triturate it in the mortar. Thus dissolve the alkanet by grinding in the scum and it will give off its essence. Then take the brilliant color prepared by the dyer – if from kermis it is better, or else from kirmnos – heat, and put this liquor into half of the scum in the mortar. Then put the wool in and color it unmordanted and you will find it beyond all description."
It's nice to have all the papyrus leaves online and available for study. An English translation may be found in Caley, E. R., "The Stockholm Papyrus: An English Translation with Brief Notes,”Journal of Chemical Education IV:8 (1926): 979-1002, conveniently posted online here. The German edition is also online here. Be sure to check out the images of this fascinating codex!
Ed. Princ. Kurt Treu and Johannes Diethart, Griechische literarische Papyri christlichen Inhaltes II, vol. 1 (MPER N.S. XVII; Vienna: Hollinek, 1993), No. 10.
P.Vindob. G 29831 is a parchment bifolium measuring 4.2 x 6.5 cm and contains two distinct texts: 1) a prayer for God to send his angel to the one wearing the amulet and 2) the text of John 1:5-6. The prayer provides justification for labeling this artifact as an amulet, and this is precisely the title the editors give it. But G.H.R. Horsley has questioned this designation vis-à-vis its original purpose. Bothered by the fact that the text of John 1:6 cuts off mid-sentence, Horsley proposed that the sheet was turned into an amulet only after the scribe realized he botched up the folio arrangement of a non-amuletic codex. But instead of wasting his efforts, he turned the problem-sheet into a fancy amulet. Originally, however, according to Horsley, the codex (which Horsley attempts to reconstruct partially) must have contained more than just the two verses. He contends that a complete continuous codex of John’s Gospel is unlikely; perhaps it only contained the prologue (1:1-18). He disagrees with the editors’ speculation that nothing followed the citation of John in Fol. 2b, which concludes with the preposition παρά.
I find Horsley’s theory problematic for two main reasons. First, it does not take into account the ritual culture of late antiquity in which ritual experts manufactured amulets for clients. Horsley’s reconstruction assumes that amulets were premanufactured but there is no evidence for this, as far as I am aware. On the contrary, amulet production was necessitated by the performative circumstances that were themselves prompted by clients looking for divine protection, healing, and the like. Moreover, many amulets are tailored to their clients, where a specific ailment is mentioned or where the client him- or herself is listed explicitly (e.g., P.Oxy. 8.1151). These features indicate that some ritual specialists produced amulets on the spot; they were thus products of the ritual performance that could be taken away and used over and over again. This omission in Horsley’s discussion is surprising, since he is aware of such ritual contexts, as evidenced by his claim that P.Turner 49 stems from a priestly or monastic milieu. Second, that the Johannine citation concludes mid-sentence is not necessarily an indication that the text continued onto another folio. Indeed, it is not uncommon to find in amulets a citation deliberately cut off in mid-sentence or mid-word (see, e.g., P.Oxy. 76.5073, P.Col. 11.294, and P.Berol. inv. 11710, P.Ant. 2.54). Likewise, beginning a citation at a particularly “random” place is also not uncommon in amulets (e.g., P.Vindob. G 26034 +30453, P.Vindob. G 2312, P.Berl. inv. 16158). Given that the prayer and the biblical citation are written by the same scribe, I think the most likely explanation is that P.Vindob. G 29831 was written as an amulet from the very beginning; Horsley’s hypothetical theory should be rejected, since it assumes too much.
But we must ask another question at this point: are we dealing with an amulet or rather a miniature codex? According to Turner’s criterion, a “miniature” codex is one whose width is 10 cm or less. Michael J. Kruger has recently problematized both categories (amulet and miniature codex), concluding that Christians viewed amulets and miniature codices as distinct literary categories. That is to say, a miniature or “pocket” codex is not synonymous with an amulet, or vice versa. According to Kruger, the category “amulet” “should be reserved for those texts that were clearly designed for magical use and not for documents that simply may have been used in a magical way.” The problem with this criterion is that it distinguishes too sharply between production and use. A fragment used secondarily as an amulet becomes an amulet, regardless of its previous use and purpose. De Bruyn and Dijkstra operate with a more inclusive approach, “taking into account not only charms and spells but also texts that are not solely or explicitly charms and spells.” The identification of an amulet is facilitated by a number of criteria, and de Bruyn and Dijkstra are careful to weigh both internal and external features in their assessment.
But the bigger question is: to what extent do form and function relate to each other? This is admittedly a modern concern, resulting from the need to classify items in neat and tidy categories. Although Kruger might be right that Christians generally distinguished between amulets and miniature codices, we know that not all did. He admits the possibility when he says that “it is possible (though rare) for a document to be both a codex and an amulet at the same time.” And even though the evidence is comparatively slim, there are several codices less than 10 cm in width that were in all likelihood designed to be amulets: P.Vindob. G 29831, P.Berl. inv. 11710, and P.Oxy. 34.2684, P.Leid.Inst. 10 and P.Oxy. 17.2065. This is especially true for the amulet currently under discussion (P.Vindob. G 29831), which begins with a prayer for protection—an obvious earmark of an amulet. Brief mention should also be made of one of the pocket codices (consisting of four wooden boards) recently discovered at Kellis. The text is a parody of Homer (LDAB 10674), but the editor wonders “whether elements of the ‘Pater noster’ were taken over in the story sketched in ll. 8 ff. Within this context, one should not only note l. 14: ‘Father Zeus, give us bread,’ but note also l. 10 where the word χρήστον may have been used intentionally as a reminder of Χριστόν.” Whether or not we can designate this miniature codex as an amulet is open to debate, but the presence of words reminiscent of the Lord’s Prayer makes it at least possible.
To be sure, we are restrcited solely to the evidence that has survived due to good fortune and so it is not clear to what extent the extant record reflects the situation of late antiquity. Nonetheless, I contend that it is reductionistic to argue that an amulet must never be a miniature codex or vice versa. I concur with Kraus’ opinion that “Kruger’s polarity between ‘miniature codex and (or better versus) amulet’ appears to be questionable.” I would add to Kraus’ critique by simply suggesting that the polarity is artificial and thus unhelpful. Book production in late antique and early Byzantine Egypt was fluid, and there is certainly no universal form or pattern for amulet production, as the evidence attests. We find amulets written in single columns and multiple columns; with short lines and long lines; on oblong materials and on square materials; on papyrus, but also on parchment, wood, and pottery. Some are folded and some are rolled, and so on. And indeed, some were bound or folded as little codices in contrast with the usual practice. Thus, we need to move beyond these categorical restrictions and restraints (amulet versus miniature codex), even though it might leave some dissatisfied.
I argue that P.Vindob. G 29831 is a miniature codex that was manufactured as such for the purpose of being used in a ritual context. To close this extended discussion, I might just note that Turner’s criterion of 10 cm or less in width has been accepted as the rule. That is, a codex’s width must fall within 10 cm if it is to be designated “miniature.” But, to quote Kraus again,
[i]s it really enough simply to stick with the dimension given by Turner (less than 10 cm broad) and is this dimension really able to embrace all the diverse manuscripts to form one single category? Does it consequently make any sense to exclude papyri that are wider, as could be the case with P.Ryl. I 3 being 10 x 10.4 cm large, while many fragmentary papyri have been included in this category on an assumed and therefore hypothetical width?
It seems to me that the “10 cm rule” needs to be reassessed.
 “Reconstructing a Biblical Codex: The Prehistory of MPER n.s. XVII. 10 (P.Vindob. G 29 831),” in Akten des 21. Internationalen Papyrologenkongresses. Berlin, 1995, vol. 1 (ed. Bärbel Kramer, et al.; Stuttgart: Teubner, 1997), 473-481.
 “Obwohl der Text auf IIv 12 mitten im Satz abbricht, folgte vielleicht nicht mehr. Dann wäre I mit der Anrufung der Beginn des Doppelblattes” (Treu and Diethart, Griechische literarische Papyri christlichen, 23).
 Of course not all amulets were produced in this way. Some amulets were cut or torn out of biblical codices and used secondarily, such as P.Col. 11.293 and P.Oxy. 64.4406. In such cases, it is unclear if a ritual specialist was involved or not.
 Turner, Typology, 30. For further discussions of miniature codices, see C.H. Roberts, Manuscript, Society, and Belief, 10-12; Gamble, Books and Readers, 235-236; Leiv Amundsen, “Christian Papyri from the Oslo Collection,” Symbolae Osloenses 24.1 (1945): 121-147, at 127-128; Kraus, “P.Oxy. V 840—Amulet or Miniature Codex? Principal and Additional Remarks on Two Terms,” in Ad Fontes, 47-67.
 Michael J. Kruger, The Gospel of the Savior: An Analysis of P.Oxy. 840 and its Place in the Gospel Traditions of Early Christianity (TENT 1; Leiden: Brill, 2005), 23-40; idem., “P.Oxy. 840: Amulet or Miniature Codex?” JTS 53.1 (2002): 81-94.
 Kruger, “P.Oxy. 840,” 93 (emphasis original).
 For fragments recycled as amulets, see P.Col. 11.293, P.Oxy. 64.4406.
 De Bruyn and Dijkstra, “Greek Amulets,” 168.
 Kruger, “P.Oxy. 840,” 91.
 Surprisingly, this amulet was not mentioned by Kruger, even though it had been published almost a decade before his study appeared. This is probably because Kruger relied solely on Van Haelst’s 1976 catalogue, as he admits (“P.Oxy. 840,” 85, 90). At any rate, P.Vindob. G 29831 offers a corrective to his statement that “prayers on miniature codices are practically non-existent” (“P.Oxy. 840,” 92).
 Colin A. Hope and K.A. Worp, “Minature Codices from Kellis,” Mnemosyne 59.2 (2006): 226-258, at 247. The Greek of ll. 8-14 run as follows: Ὣς εἰπὼν πυλέων ἐξέσσυτο λευκὸς ἀλέκτωρ | τῷ δ’ ἁμ’ Ἀλέξανδρος πιάσας παρέδωκε μαγείρῳ | ὁ δὲ μάγειρος ἑψήσας καὶ γευσάμενος ἔλεγε, “Xρηστόν! | Τρῶες καὶ Λύκιοι καὶ Δάρδανοι, δεῦτ’ ἐπὶ δεῖπνον· | ἀνέρες ἔστε, φίλοι, μνήσασθε δὲ μάππαν ἐνεγκεῖν. | Αἰσθίετε πάντες καί μοι καταλίψατε ὀστοῦν. | Ζεῦ πάτερ, ἢ ἄρτον μοι δὸς ἢ τυρίον ὀπτὸν.
 Kraus, “P.Oxy. V 840,” 59 (emphasis original).
 Kraus, “P.Oxy. V 840,” 57.
In P.Col. 11.294, an amulet with the text of a prayer and a citation of Ps 150, there is an interesting nomen sacrum (with overlining) for "Abraham" on the verso, l. 11:
This is one I haven't seen before. It seems to be an abbreviation of Ἄβραμος, the spelling of which is attested. The editor (Timothy M. Teeter) notes two other possible occurrences of the nomen sacrum in P.Bodmer VII 12.14 and P.Bodmer VIII 49.12. Otherwise, this may be the only example. One thing I have learned from my study of Christian amulets is that scribes wrote nomina sacra--among other things--in strange ways. They were rarely consistent in employing abbreviations and supralinear strokes. In one line, for example, you will encounter a sacred name in abbreviated form and then in the very next line you will see it written in scriptio plena. My forthcoming dissertation (which I am presently wrapping up for good!) documents many of them. So, an unusual nomen sacrum is not a strange thing in amulets. In any case, I'm wondering: has anyone else encountered an example of a nomen sacrum for Abraham, other than those mentioned above? Teeter published his edition of P.Col. 11.294 in 1998 so perhaps another example has appeared since then.