The paper shows the possibility of producing a thermal insulating composite based on basalt fibers and saponite-containing mining waste. A method for manufacturing thermal insulating composites from hydro-mass with different contents of the mixture components is proposed. Basalt fibers were used as a filler, and pre-mechanoactivated saponite-containing material (SCM) was used as a binder. It was found experimentally that depending on the composition of composites, the coefficient of thermal conductivity varies from 0.1109 to 0.1342 W/(m•K), and the compressive strength – from 0.45 to 0.93 MPa. In addition, it was found that thermal modification of composites at temperatures up to 1200°C significantly (up to 3 times) increases the compressive strength of composites, while not affecting the coefficient of thermal conductivity. The experiments to determine the conductivity of the composite “basalt fiber – SСM” depending on its moisture content showed that the obtained composite is characterized by intense and linear increase in the values of conductivity when the humidity of the sample to 12% and further increase in humidity practically does not change the values of the coefficient of thermal conductivity. Comparison of the studied thermal insulation composite with known structural thermal insulation materials in terms of its thermal insulation and strength characteristics showed that it is comparable to gas and foam blocks. It should also be noted that this material is environmentally safe and can withstand high temperatures without collapsing.