The mineral content in the exoskeletons varies with the species and with the location in the exoskeleton. The ratios of calcium to magnesium and of carbonate to phosphate are also variable. Raabe et al. studied the cuticle of Homarus americanus by thermogravimetry and found a loss of water of 19.8 wt%, a content of organic matrix of 29.2 wt% and a loss of CO2 of 36.5 wt%. By energy-dispersive X-ray spectroscopy, carbon, oxygen, sodium, magnesium, phosphorus and calcium were found [10], in good accord with our results.