Yes it is a crystal, I do not remember the ID but the database is cambridge crystallogaphic database at
and if you type in 1,3,5-Trinitroperhydro-1,3,5-triazine as your query, you will get the crystal structure. Or you can have a look at the original paper which is uploaded for this alpha RDX crystal
C. S. Choi, and E. Prince, Acta Crystall B 28, 2857 (1972).
This is the citation to that paper which contains the original alpha RDX crystal structure.