A highly-priced calcareous spar, calcium hydrosulfate, could be creamy white or even transparent.
The ancients used it to make vessels for expensive ointments, and other uses; In the Philadelphia University Museum there is an alabaster lamp from Ur, dating back to the time of Abraham.
In the palace of Susa, of King Artaxerxes, it was part of the paving (Est. 1:6). In the gospels the anointing of Jesus' feet is only mentioned in two cases, in the house of Simon the Pharisee (Lk. 7:36-50), and shortly before being betrayed, in the house of Simon the leper (Mt. 26:6-13; Mr. 14:3-9; cp. Jn. 12:1-8).
"Breaking" the glass probably refers to the breaking of the seal.
Meaning of ALABASTER
A highly-priced calcareous spar, calcium hydrosulfite, may be creamy white or even transparent.


