A spindle for a mud pulse telemetry tool includes a seal section having an outer surface for contacting a lip seal of a spindle housing in which the spindle is mounted; a top section attachable to at least part of a valve assembly for generating mud pulses; and a base section having a proximal end attachable to a drive motor for moving the spindle and a distal end attachable to the top section such that the annular seal is fixed between the top and base sections. The seal section can be made of a ceramic material such as yttrium-stabilized zirconia.