vitrinite

n

the predominant maceral in most coals of intermediate reflectance occurring as substantial volumes of more or less uniformly reflecting material or as a matrix enclosing particles of other macerals and mineral matter or as particles or bands intermixed with other maceral fragments.

DISCUSSION — Because most vitrinite is derived from the cellular, structural tissues of plants, it may exhibit relict cell structure. The reflectance of vitrinite is related to the rank of the coal in which it is found. Reflectance increases (from around Ro = 0.3 % in lignitic coals) in parallel with the increase in fixed carbon yield associated with increasing rank. Because many of the properties of typical coals reflect the properties of the dominating vitrinite, it is common practice to estimate coal properties and process behaviors by measuring the reflectance of a representative sampling of vitrinite in the specimen according to procedures described in Test Method D2798. Pseudovitrinite, a certain variety of vitrinite, is differentiated by some practitioners. It exhibits slightly higher reflectance than most of the vitrinite in the coal and is commonly slitted, with indistinct remnant cell structure and angular or jagged edges. Pseudovitrinite has been postulated to be less thermoplastic in the coking process. The term vitrinite is currently used as both a maceral and maceral group.