Persistent data structures in Scala

Question

Are all immutable data structures in Scala persistent? If not, which of them are and which not? What are the behavioural characteristics of those which are persistent? Also,

Answer 1

Please have a look at these excellent articles by Daniel Spiewak:
http://www.codecommit.com/blog/scala/implementing-persistent-vectors-in-scala
http://www.codecommit.com/blog/scala/more-persistent-vectors-performance-analysis

He's also referring to the Clojure implementation.