Scientia Sinica

178 SCIENTIA SINICA Vol, V

ature range of the experiments was 250-550°C. Pressure was calculated from the initial degree of filling and temperature. The initial charge consisted of 4 mixture of simple chemical compounds. It was well mixed and the solution was tested for its pH value both before and after each run. Most runs lasted for two or three days, during which period equilibrium was thought to have been reached.

Since chloritoid, the more widespread member of brittle micas, -contains ferrous iron, an attempt was made to introduce the latter into the initial charge. Iron was present in the form of carbonate or oxalate. However, after each run it invaribly formed magnetite and thus did not take part in the crystal structures of the synthetic products. The condition within the bomb could not

Table I. Synthesis of Brittle Micas (Degree of Filling 0.2)

Oe

; Ingredients : pH | pH Expt. |Temp.| Time | Pressure : Other Alkalies No. |in C°}in hrs.jin kg/cm* i022 AlzQg: CaO Added peters ae Products 1 420 63 305 eee et 1 8.5 7 Margarite & : boehmite 2 420 68 305 2 2 5.5 5 Boehmite & ; (CaCl) Margarite 3 410 67 290 2 2; 1 6 | 6 Boehmite & ; (CaCOg) : Margarite 4 420 85 340* 2) Zea 1 NaCOz 12 11.5 | Cancrinite 5 | 410 66 290 2 2 1 Na OH 10 9 Cancrinite 6 370 71 220 2 2 1 Na OH 12.5 | 10.5 | Cancrinite 7 475 70 390 2 2 1 Na OH 13 | 11.5 | Cancrinite & Unknown A 8 420 68 305 2 2 1 NaCl 8.5 Boehmite & margarite 9 420 90 305 2 2% 5 5 4.5 | Margarite (CaCl,) 10 420 95 305 2 2: 5 7.5 | Calcite & (CaCOs) margarite 11 420 62 305 2 2: 5 9 7 Unknown A 12 415 46 295 2 D 5Na,O as NaCl| 6.5 6 Boehmite & Paragonite 13 420 67 305 203 1 = 5 3MgO 6.5 5 Serpentine (CaCl,) 14 | 420 67 305 22 4 5 5 Margarite-like (CaCl) 15 320 70 120 2 2s See 5 5 Boehmite (CaCle) 16 485 47 395 D2 > 5 5 Margarite (CaCle) G7, 350 96 170 2h 2 i 5 5 5 Boehmite (CaCla) 18 370 16 220 D2 5 5 5 Boehmite & days (CaCls) trace of margarite 19 540 44 460 22 5 5 margarite (CaCls) !

*Degree of filling=0.4.