Figure 6: The plane tiled by T2 triangles. Left: alpha phase, in which the
triangles are stacked diagonally. Right: beta phase, in which they are
stacked in columns.
The next larger triangles, T2, can cover the plane in two different ways. One, which could be designated the alpha phase, strings the tiles out along diagonals, as shown in the left mosaic of Figure 6. The other, similar to the T1 mosaic, arranges the T2 tiles in columns, for which there is only one way to avoid unwanted sequences of three ones in a row. It constitutes the beta phase, shown in the right mosaic of the same figure.
The density of the alpha phase is 
or 62.5%, of the beta phase 
or 67%. In spite of the more favorable densities, neither mosaic is ever a
predominant feature of evolutions from random initial configurations.