In reply to a forum query, BioWare’s Allison Berryman has sourced some information on the issue:
I asked Jason Attard (Senior Game Balance Designer) about whether or not we intend to bring the white crystals back. He said that we do intend to make this crystal available again in the future, but we do want it to remain very rare even when we do.
So there you go – they won’t be easy to get but they may be back. What are your thoughts?