The invention concerns a geolocation method (200) and an anti-theft tracer (1) for inserting in the butt (21) of a firearm (2), said geolocation method (200) making it possible to determine the geographical coordinates of said anti-theft tracer (1) and to detect an unwanted movement. The geolocation method (200) also makes it possible to communicate with a device in order to transmit data relating to the movement of the anti-theft tracer (1). The present invention also concerns such an anti-theft tracer (1) which comprises, in particular, damping means (102) for reducing the vibrations generated by use of the firearm (2) and transmitted to the electronic components of said anti-theft tracer (1).