Boron, alpha-rhombohedral

X-ray Identification. A typical x-ray analysis is shown in Table V. The diffuse lines observed in the x-ray pattern correspond to the alpha rhombohedral structure. This is the low-temperature form of boron. However, the structure is not well developed as indicated by the broad lines. The boron may have been in the process of changing from an amorphous boron. 

The story is far from complete. The two recent experimental studies of the relative stability of alpha- versus beta-rhombohedral boron gave conflicting results [55, 56]... 

---