One hundred and ninety three glass fragments from the canabae in York were analysed (first to fourth centuries). They fall into six compositional groups: antimony colourless (Sb), highmanganese (high-Mn), low-manganese (low-Mn), mixed antimony and manganese (Sb-Mn), high iron, manganese and titanium (HIMT) and plant ash. Some groups represent production groups, some of which appear to be in limited supply in this western outpost, but are more prevalent elsewhere, and others reflect changing supply mechanisms. The majority of glasses fall into groups that demonstrate extensive recycling of glass. This has important implications for determining provenance using trace elements and isotopes. KEYWORDS: ROMAN GLASS, NATURALLY COLOURED, COLOURLESS, ANTIMONY, MANGANESE, PRODUCTION GROUPS, RECYCLING, BRITAIN, ICP-AES THE ROMAN GLASS FROM COPPERGATEAlthough perhaps best known for its Viking deposits (Hall 1984), the site at 16-22 Coppergate, York also produced deposits rich in Roman finds, including glass. The putative glass-making or glassworking remains have already been published (Jackson et al. 2003), but the site also yielded a large assemblage of glass fragments, typical of a consumption assemblage from the first to fourth centuries and which is probably unrelated to the glassworking debris found at the site (Jackson 1992). The assemblage comprises forms that can be dated from the first to fourth centuries and represents a microcosm of glass found in the western provinces at this period. The scale of the assemblage is not surprising: Eboracum (Roman York) was an important Roman centre in Britain, occupied from ad 71 to 410, housing a fortress and large manufacturing and civilian districts. Coppergate was outside the fortress, within the city walls, and is likely to have been a trading or manufacturing area as part of the canabae, although Roman remains from the site have been largely robbed (Mainman 1990). Within scientific research into Roman glass, the composition of colourless glass has been well studied, as has later glass from the mid-third and fourth centuries onwards (e.g., Freestone et al. 2005;Jackson 2005;Paynter 2006;Silvestri et al. 2008; Jackson 2009, 2010;Gallo et al. 2013), but naturally coloured glass of the first to third centuries has often been neglected. 'Naturally coloured' here describes transparent glass with a range of mostly
58, 1 (2016) 68-95blue-green hues caused by small amounts of iron oxide in the glass (Price and Cottam 1998), as opposed to containing intentionally added colourants. The Coppergate assemblage is significant because it includes naturally coloured, as well as colourless, glass in many common forms from a long-lived site, including many fragments that date from the second and third centuries. This study is therefore able to analyse a large corpus of material from a single site to demonstrate the availability of different raw glass types, and the extent of recycled glass within the trading network operating throughout the Roman world. By identifying changing glass composi...