Identification of pigments and gemstones on the Tours Gospel: the early 9th century Carolingian palette

Abstract

Twelve gemstones set into the cover of an elaborately decorated leather-bound manuscript, the Tours Gospel, 'Evangelia Quatuor', held in the British Library (Add. MS. 11848), were identified by Raman microscopy to be composed of silica, amethyst, emerald (probable, 3), iron garnet (3) and sapphire (3), one not being identified. The brilliant illuminations within the manuscript (ca 825 AD) were established by Raman studies at 215 locations on 13 folios to have been painted with a restricted palette, which included carbon black, indigo, lead white, minium, orpiment and vermilion, together with certain mixtures of the above pigments. Gold was also used but, notably, not lazurite. The palette was compared with those found for the earlier Lindisfarne Gospels (ca 715 AD), part of a later Anglo-Saxon manuscript (ca 920 AD), a Paris Bible (1267 AD) and certain Gutenberg Bibles (1455 AD).

Characterisation of inorganic pigments in ancient glass beads by means of Raman microspectroscopy, microprobe analysis and X‐ray diffractometry

“…As demonstrated in Fig. 9, the lead-dominated beads are characterized by a very typical band with high intensity at 980 cm 1 , clearly indicating that the glass matrix is formed by a network of two-dimensional chains of SiO 4 tetrahedra with mainly two NBOs. 20,21 In contrast, the potassium-or sodium-dominated beads show a high intensity at about 950 cm 1 , deriving from SiO 4 units with mostly one NBO and a sheet-like network.…”

“…By focussing the laser beam directly on the microcrystals in the glass matrix, one obtains Raman bands at 150, 186, 197, 212, 494 and 627 cm 1 (Fig. 5), similar for all microcrystals investigated in all red and orange samples, though not always of the same quality in resolution.…”

“…In the white layers of the two blue coloured beads, high SnO 2 contents can be observed (Table 1). The Raman spectra of these white layers show peaks at 471, 630 and 773 cm 1 (Fig. 2) and therefore indicate SnO 2 , cassiterite, 10 as the colouring agent and opacifier of the white interlayers.…”

“…A representative Raman spectrum of sample 196/5 (Fig. 8) includes the typical cuprite bands at 218, 494, and 624 cm 1 .…”

“…The advantages of being rapid, non-destructive, sensitive and spatially refined make it most valuable for the in situ analysis of inorganic pigments. Many reports have been published dealing with Raman spectroscopy on pigments in ancient manuscripts, 1 paintings, 2 faiences 3 or mosaics. 4 In this paper we present the identification of pigments in ancient glass beads by means of Raman microspectroscopy.…”