Allotropic and high-pressure

No other element forms more solid allotropes than sulfur. At present, about 30 well characterized sulfur allotropes are known. These can be divided into ambient pressure allotropes and high-pressure allotropes depending on the conditions during preparation. While the molecular and crystal structures of the ambient pressure allotropes are known in most cases, this does not apply to all of the high-pressure forms. Therefore, in the following the two groups are described in separate sections of this chapter. 

Parts C of the tables present crystallographic data for allotropic and high-pressure modifications of the elements. The left-hand columns contain data for allotropic modifications that are stable at a pressure of 100 kPa over the temperature ranges indicated, and the right-hand columns contain data for modifications stable at higher pressures as indicated. The modifications stable at 100 kPa are denoted by Greek letters... 

Table 2.1-6C Elements of the first period (hydrogen and helium). Allotropic and high-pressure modifications...

Table 2.1-7B(a) Elements of Group lA (CAS notation), or Group 1 (new lUPAC notation). Crystallographic properties (see Table 2.1-7C for allotropic and high-pressure modifications)... 

Table 2.1-17C Elements of Group VIA, or Group 16. Allotropic and high-pressure modifications, cont. ...

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