An apparatus and method for the turbulent mixing of gases are described. The invention has particular application when it is desired to produce a gas mixture including a very small quantity (ppm or less) of at least one component gas and/or wherein there is a substantial density difference between the component gases to be used to make up the gas mixture. The apparatus comprises: a tubular housing; at least two orifices or jets located near one end of the housing, through which gases to be mixed can enter the interior of the housing, the orifices or jets being oriented so that a first portion of gas flowing from a first orifice or jet will directly impact a second portion of gas flowing from a second orifice or jet, whereby frictional mixing of the gas components is achieved, further, the centerline of the first orifice or jet is offset from the centerline of the second, opposing orifice or jet, so as to produce a swirling action within the tubular interior of the gas mixer; and an exit opening at the opposite end of the tubular housing.