A silicate mixture and a combustion accelerator increase combustion efficiency in a combustion engine. The silicate mixture is formed by mixing a first component including one or two or more materials selected from silicon compounds including silicon, glass, and quartz, and a second component including one or two or more materials selected from materials formed by sintering a silicate mineral at a temperature of 1300° C. or higher and 2000° C. or lower and ores emitting a terahertz wave.