Vickers hardness and Young's modulus of the different phases of High Intensity Discharge Lamp sea] has been characterized using depth-sensitive micro-indentation. Based on the length of the cracks initiated during indentation critical fracture toughness and stress anisotropy has been calculated. To reveal the brittle properties of the seal a cracking statistics method has been developed which allows characterization of samples with characteristic size below I mm. Vickers hardness and Young's modulus is homogenous in the seal. There is a tangential tensile stress and compressive radial residual stress in the sealing. Cracking proper-ties of the two main phases of the sealing were found to be different.