This Bureau of Mines report reviews and summarizes recent studies of the rates of chlorination of aluminous resources with CO and cl2 mixtures with and without cocl2. No reaction mechanism could be obtained from the existing results; however, diffusional barriers in the gas and solid layers probably control the chlorination rate in thermogravimetric experiments. Fluidized beds of particles smaller than 0.1 Mm appeared to show very little solid layer diffusional barrier. For optimum chlorination the particle size should probably be less than 8 mm, the calcination temperature approximately 700 deg c, and the chlorination temperature from 650 deg to 750 deg c. Relatively rapid chlorination with cocl2 in thermogravimetric experiments was attributed partly to the simultaneous supply of reductant and chlorinator by one gas to the sample reaction site. Comparable results for chlorination of fluidized beds with cocl2 are not available. Equimolar mixtures of CO and cl2 produced the optimum rate of reaction. Addition to the calcine of 10 to 20 wt- pct nacl accelerated the rate of chlorination, and addition of sicl4 to the gas mixture decreased the rate of chlorination of sio2 drastically, but at the expense of chlorination of significant fractions of al2o3. Further research in various areas is suggested.