Disclosed is a composite particle for use in a marking that is suitable for identification/authentication purposes. The particle comprises at least one superparamagnetic portion and at least one thermoluminescent portion coated with an thermoisolating portion. Optionally also a thermoconductive portion between the superparamagnetic and thermoluminscent portions.

Phosphors include a CaAlSiN.sub.3 family crystal phase, wherein the CaAlSiN.sub.3 family crystal phase comprises at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb.