The Procurement of Rhum Bloodstone and the Rhum Bloodstone Exchange Network – a Social Territory in the Scottish Inner Hebrides?
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The procurement of Rhum bloodstone and the Rhum bloodstone exchange network – a social territory in the Scottish Inner Hebrides? Torben Bjarke Ballin Abstract ‒ The purpose of the present paper is to discuss Rhum bloodstone and the distribution of archaeological bloodstone throughout the Scottish Inner Hebrides. The main aim is to discuss the observed distribution patterns, bloodstone procurement and exchange, and the social territory defined by bloodstone distribution. Key words ‒ archaeology; Inner Hebrides; Scotland; Rhum bloodstone; exchange networks; social territories; lithic raw material procure- ment; lithic raw material terminology Titel – Das Rohmaterial ‚Rhum Bloodstone‘: seine Beschaffung und sein Tausch-Netzwerk – Hinweis auf ein soziales Territorium auf den Inneren Hebriden (Schottland)? Zusammenfassung – Der Zweck des vorliegenden Aufsatz ist die Diskussion von “Rhum bloodstone” und die Verbreitung archäologi- scher Artefakte aus ‘bloodstone’ auf den Schottischen Hebriden. Dabei richtet sich der Fokus besonders auf erkannte Verteilungsmuster, die Beschaffung und den Austausch von ‘bloodstone’ und das durch die Verbreitung von ‘bloodstone’ festgelegte Sozialterritorium. Schlüsselwörter – Archäologie; Innere Hebriden; Schottland; Rhum bloodstone; Tauschnetzwerke; Sozialterritorien; Beschaffung von Steinrohmaterial; Terminologie von Steinrohmaterial Introduction What is Bloodstone – the basic lithic raw material terminology Since the publication of Wickham-Jones’ volume on the Kinloch site on the Isle of Rhum in the Scot- Inspection of the archaeological and geological lit- tish Inner Hebrides (1990), it has been obvious that erature shows that, in general, archaeologists and Rhum bloodstone from an archaeological point of geologists agree on the basic notion that blood- view is an interesting lithic raw material, and that stone is a form of jasper (chalcedony), and that as the distribution of this raw material might poten- such it is a form of crypto- (or micro-) crystalline tially enlighten us on a number of points, such as quartz, or silicon dioxide (eg, HEDDLE, 1901; DU- lithic raw material procurement, exchange net- RANT ET AL., 1990; LUEDTKE, 1992; PELLANT, 1992). It works, and social territories. However, at the time may be discussed whether it is a form of chert, as only a small number of bloodstone-bearing sites the definitions of chert and flint vary from coun- were available (CLARKE & GRIFFITHS, 1990), and the try to country (LUEDTKE, 1992, 5). distribution of these sites told us little more than In general terms, two main sets of definitions that some bloodstone, once quarried or collected, of chert exist, namely ‘American’ and ‘British’ was transported off Rhum. definitions, where American nomenclature per- Today, a quarter of a century later, many more ceives chert as more or less synonymous with the bloodstone-bearing sites are known (see fig. 14 term ‘crypto-crystalline quartz’ and includes flint and Appendix), and it is now possible to discuss (LUEDTKE, 1992, 5), whereas British nomenclature the distribution of archaeological bloodstone in defines flint and chert as two different forms of a more meaningful manner. The purpose of the crypto-crystalline quartz, with flint having been present paper is therefore to, first, define blood- formed in Cretaceous chalk formations and chert stone geologically; then, describe the geological in all other formations. Chalcedony (and thereby and archaeological distribution of this raw mate- bloodstone) is commonly (American nomencla- rial; and, finally, attempt to interpret the distribu- ture) seen as forming part of the chert family (eg, tion patterns, to the degree the evidence allows LUEDTKE, 1992, 5), whereas others (British nomen- this. The main questions relate to the character clature) see it as neither a chert nor a flint but a of the territory defined by the distribution of ar- separate type of crypto-crystalline quartz, a min- chaeological bloodstone, as well as the exchange eral (eg, PELLANT, 1992, 88). network responsible for this distribution. In addition, there exists a third set of defini- tions of lithic raw materials, which has been al- Received: 11 Jan 2018 Archäologische Informationen 41, 2018, 241-254 accepted: 28 April 2018 CC BY 4.0 published online: 28 May 2018 241 Torben Bjarke Ballin most entirely overlooked in Anglo-American Scotland, this choice of nomenclature is relevant lithic research, namely the Central European defi - to discussions of procurement and exchange pat- nitions. PŘicHystal (2010; also see GÖTZE, 2010) terns as it allows the various forms of crypto-crys- suggests the following terminology: talline quartzes to be grouped geographically and — Siliceous sediments (silicites) – originating from in relation to one or the other form of bedrock (see chemical, biochemical or diagenetic precipita- the following chapter). tion of SiO2, including chert, fl int, radiolar- The chalcedony family may be subdivided into ites, spongolites, lydites, phtanites and limnic a number of different sub-categories on the basis silicites; the decisive factor […] is fi nding fos- of colours and patterns, such as chalcedony proper sils or microfossils […] in the silica substance. (grey or bluish-grey), jasper (usually red), carnel- — Minerals of SiO2 – this group includes mem- ian (brown), agate (characterized by concentric bers of the quartz family (milky quartz, rock banding), and bloodstone/plasma (green jasper). crystal, smoky quartz, citrine, etc.), members of Bloodstone is also called heliotrope, and heliotrope the chalcedony family (chalcedony, agate, jas- and plasma are frequently found in the same geo- per, bloodstone, carnelian, etc.), and opal, and logical environments (HALL, 2000, 93), such as for samples never contain fossils or microfossils. example around the extinct volcanoes on the Isle1b of — Natural glasses – this group includes obsidian, Rhum in the Scottish Inner Hebrides. pitchstone, and tektites (eg, Moldavite and In terms of specifi c geological attributes and Libyan Desert Glass). formation, chalcedony is generally defi ned in the — Clastic silica sediments – chert, sandstone, etc. following manner: “A microcrystalline variety of — Other rocks – includes a number of altered rocks silicon dioxide […] usually occurring as mammilary The existence of these different sets of defi ni- or botryodal masses. The colour is highly variable. This tions occasionally makes archaeological discus- mineral forms in cavities in rocks of different types, es- sions of assemblages based on crypto-crystalline pecially lavas. Much chalcedony develops at relatively quartz slightly confusing, not least in terms of low temperatures as a precipitate from silica-rich solu- procurement and exchange patterns. Some Euro- tions” (PELLANT, 1992, 88). Heddle (1901, 57) defi nes pean archaeologists choose to apply American no- plasma as: “Chalcedony stained bright green by the menclature whereas others apply British nomen- uniform admixture with Delesite or Celedonite. Lustre, clature, with a small number of archaeologists greasy to horny.” He (ibid.) defi nes heliotrope in preferring the Central European nomenclature. In the following fashion: “Chalcedony stained various archaeological research, the problem is that ana- shades of green, dark to leek-green, by admixtures with lysts tend to apply one or the other of the main Celedonite, and, when sprinkled with red spots, becomes geological terminologies, not realizing that even Bloodstone; when these from confl uence, become blotch- geologists disagree amongst themselves on these es, it is Heliotrope” (fi g. 1). matters, where we, as archaeologists, should con- sider independently which set of defi nitions may serve our archaeological purposes (discussions/ interpretations) best. This is not the place for a general discussion of fl int and chert, or crypto-crystalline quartz, but it is suggested that, to discuss matters such as pro- curement and exchange patterns most sensibly, lithics specialists may be served best by following Přichystal (2010), who perceives chalcedony (and thereby bloodstone) as a form of crypto-crystalline quartz different to fl int and chert (a mineral). Fol- lowing Přichystal (2010), fl int and chert are sedi- mentary rock forms (‘silicites’), formed in sedimen- tary rock formations, and the silica tends to derive from organic sources. Chalcedony/bloodstone, on the other hand, is defi ned by Přichystal (2010), and also Pellant (1992, 88), as being a crypto-crystalline type of quartz, most commonly formed in lavas and related rock formations by the solidifi cation Fig. 1 Flake of gem-quality bloodstone showing the characteristic of hydrothermal fl uids not of organic origin. In red spots and fi laments. Purchased in jewellery shop. 242 Rhum bloodstone and ts exchange network – a social territory in the Scottish Inner Hebrides? In their discussion of bloodstone from Rhum (in WICKHAM-JONES, 1990), DURANT ET AL. (1990) states that “… there is little agreement as to termi- nology in the geological literature, but technically the term bloodstone should be reserved for the fine-tex- tured dark green nodules that are shot through with red.” However, they also conclude that: “… pre- historic people apparently made no distinction between the formal varieties (ie, plasma or heliotrope [blood- stone]).” Furthermore, in terms of characterizing pieces of worked plasma/heliotrope in archaeo- logical assemblages, it would be entirely unreal- istic to attempt to distinguish between these two