This work consists of a scientific documentation of the eighteenth-century Chiadma carpet, currently on display at the Dar Si Said Museum in Marrakech. It is the earliest known carpet in Morocco, an example of Morocco’s tangible cultural heritage, commonly known as “Zarbia”. The study included scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) measurements, optical reflectance, 3D fluorescence, surface-enhanced Raman spectroscopy (SERS), and confocal µ-Raman spectroscopy. Since the few studies carried out on the Moroccan antique carpet heritage have focussed exclusively on the artistic aspects, the aim of the present work is to apply an integrated and non-destructive analytical approach to characterise the dyes used and then provide response elements on the dyeing protocol adopted. The wool fibres analysed by electron microscopy showed a certain degree of degradation/tearing and the presence of some impurities, while EDS allowed the detection of mordants in red and yellow fibres. In terms of dyes, the analyses highlighted carminic acid from cochineal extract in pinkish red shades, flavonoids from weld or Daphne gnidium in yellow shades, and natural indigo from Isatis or Indigofera tinctoria in blue shades. Mixtures of yellow dye plants with either madder or indigo were present in orange-yellow and green colours, respectively. The non-invasive techniques allowed rapid and real-time analysis, but their specificity was limited in terms of tracing the dyes to their botanical origin, i.e. the yellow-dyeing plants on aged fibres. On the other hand, the study highlighted the mastery of natural dye processing and provided relevant data to support any restoration of this prestigious carpet, which has suffered from ancient, non-controlled indoor conditions.

This study investigates the heavy metal composition (Cd, Pb, Fe, Li, Cu, Zn, K, Na, Ca) of Rubia tinctorum (L.) roots collected from Souk Attarine in the historic medina of Fez, Morocco. Thermal analysis (DTA/TGA) revealed significant mass losses within specific temperature ranges. Samples were calcined at 110 °C, 325 °C, 450 °C, and 600 °C. FTIR spectroscopy confirmed the degradation of organic matter and the formation of calcite and silica at higher temperatures. UV–Vis spectroscopy revealed π–π* transitions in the 250–280 nm range and n–π* transitions between 420–550 nm, indicative of alizarin-type chromophores. For elemental quantification, samples were acid-digested and analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The ICP-AES method exhibited excellent linearity (R² > 0.998) over a concentration range of 0–50 mg L-1, depending on the element. Limits of detection (LOD) ranged from 0.003 to 0.066 mg/L, and limits of quantification (LOQ) from 0.010 to 0.083 mg L-1, demonstrating high sensitivity and precision. X-ray diffraction (XRD) confirmed the presence of calcite (major peak at 2θ = 29.4°) and secondary quartz in the calcined samples. High levels of essential elements (Ca, K, Fe) and Cd and Pb concentrations below WHO toxicity limits confirm the ecological safety and analytical value of Rubia tinctorum as a natural dye source.