A new SiC polytype, 45 Rb

The stacking sequence of a new SiC polytype 45Rb, which was synthesized at room temperature is (433212)₃. This implies that the Zhdanov symbol 1 in the stacking sequence, except for the 2H polytype, might be a special characteristic of the structure of SiC grown at low temperatures. If this is true, the recently reported 5H polytype SiC found in limestone, dolomite and alluvial deposit, which can be deduced as (41) stacking, may be authigenic and might have grown at a low temperature. This idea may suggest the general distribution of SiC in limestone and in other low- temperature deposits. Unmetamorphosed limestones of about 20 localities were examined, and SiC was found in seven of those localities, although the 45Rb and 5H polytypes have not been found yet in these samples.