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This article systematises and generalises little known and unpublished data on the composition, location, character and scale (intensity) of the free gases emitted when a major loparite deposit confined to the Lovozero nepheline-syenite massif is drilled or mined. This type of gas is of great practical interest, as emissions of combustible and explosive gas components need to be predicted and gas-safe drilling facilitated. Data from the Karnasurt loparite(-Ce) rare metal mine show that CH4 and H2 are dominant in the free gas composition, their C and H being characterised by rather heavy isotope compositions that become lighter from the transition of methane to ethane. The free gas volume has been estimated as 0.2-1.6 m3 of gas per 1 m3 of undisturbed rock. The gas recovery of walls in underground workings has been up to 0.2 ml/min/m2 for CH4 and 0.5 ml/min/m2 for H2 in several years after their heading. The discharge that characterises the gas emission intensity is up to 300 ml/min from some shot holes (1.8-2 m deep and 40 mm in diameter), but values 1-2 order of magnitude less predominate. The discharge time in some sections varies from several days to 20 years. The overpressure of gases towards the air mainly does not increase above 100 kPa, sometimes reaching 120 kPa. Combustible and explosive hydrogen-hydrocarbon free gas can accumulate in the air of underground workings and cause accidents, disrupting the workflow. On the positive side, the prospect has been raised of predicting rock bursts and other dangerous geodynamic phenomena by identifying and developing gas-geochemical and gas-dynamic precursors. Statistical relationships have been established between gas composiitons and the elastic and mechanical properties of Lovozero rocks and ores, and experimental stressing of nepheline-syenite samples have shown increwases in radon and H20hydrocarbon emission, reaching a maximum before sample breakdown., This article systematises and generalises little known and unpublished data on the composition, location, character and scale (intensity) of the free gases emitted when a major loparite deposit confined to the Lovozero nepheline-syenite massif is drilled or mined. This type of gas is of great practical interest, as emissions of combustible and explosive gas components need to be predicted and gas-safe drilling facilitated. Data from the Karnasurt loparite(-Ce) rare metal mine show that CH4 and H2 are dominant in the free gas composition, their C and H being characterised by rather heavy isotope compositions that become lighter from the transition of methane to ethane. The free gas volume has been estimated as 0.2-1.6 m3 of gas per 1 m3 of undisturbed rock. The gas recovery of walls in underground workings has been up to 0.2 ml/min/m2 for CH4 and 0.5 ml/min/m2 for H2 in several years after their heading. The discharge that characterises the gas emission intensity is up to 300 ml/min from some shot holes (1.8-2 m deep and 40 mm in diameter), but values 1-2 order of magnitude less predominate. The discharge time in some sections varies from several days to 20 years. The overpressure of gases towards the air mainly does not increase above 100 kPa, sometimes reaching 120 kPa. Combustible and explosive hydrogen-hydrocarbon free gas can accumulate in the air of underground workings and cause accidents, disrupting the workflow. On the positive side, the prospect has been raised of predicting rock bursts and other dangerous geodynamic phenomena by identifying and developing gas-geochemical and gas-dynamic precursors. Statistical relationships have been established between gas composiitons and the elastic and mechanical properties of Lovozero rocks and ores, and experimental stressing of nepheline-syenite samples have shown increwases in radon and H20hydrocarbon emission, reaching a maximum before sample breakdown.