The present invention relates to a mechanochemically carbonated magnesium silicate which has a BET surface area within the range of 20 to 100 m2/g, preferably 30 to 80 m2/g, more preferably 40 to 70 m2/g, most preferably 45 to 65 m2/g and/or an amorphous content as determined by XRD of at least 30 wt. %, preferably at least 40 wt. %, more preferably at least 50 wt. %, even more preferably at least 60 wt. % a CO2 content of at least 3 wt. %. The invention further relates to methods of its production and uses thereof, for example as a filler in polymers. The compositions comprising the mechanochemically carbonated magnesium silicate and a polymer (such as a polyolefin) provide the benefits of being a CO2 negative material having excellent functional properties which can be used for a variety of purposes, for example as a component of clothing or apparel, or as a component of backpacks such as a buckle.