X-type Asteroid - Tholen Classification

Tholen Classification

In the Tholen classification the X-group contains the types:

  • E-type
  • M-type, the largest grouping
  • P-type

Since in this scheme the albedo is crucial in discriminating between the above types, some objects for which albedo information was not available were assigned an X-type. An example of this is 50 Virginia.

Read more about this topic:  X-type Asteroid