The issue of what was in the alabaster (jar) of Mark 14,3 is notoriously difficult. Here's the phrase in question:
avla,bastron mu,rou na,rdou pistikh/j polutelou/j(
A few English versions, such as the ESV ("...an alabaster flask of ointment of pure nard, very costly,..."), simply avoid taking a position on what the πολυτελους is doing in the phrase and simply render it separately.
Most English versions, however, want to take it as something like:
"...an alabaster jar of expensive ointment of pure nard..."
Note that this rendering decides to take the πολυτελους as modifying μυρου, but if this is the case, then the proper analysis of πολυτελους should be a genitive NEUTER (not FEM) singular. (Note that πολυτελους could be either FEM or NEUT.)
My point: none of the Greek morphological schemes acknowledge that it could be a NEUT even though most English renderings treat it as such. I'm thinking this is one of those cases where an either FEM or NEUT should be provided in the analysis.
BTW, I usually like the NRSV, but their rendering here is really not satisfactory: "...an alabaster jar of very costly ointment of nard, ..." The problem here is that it seems to be omitting πιστικης altogether.