From an unused root (probably meaning to glisten); white marble or perhaps alabaster -- red (marble).
H923. bahat
בַּ֫הַט noun [masculine] a costly stone, perhaps porphyry (compare Egyptian behiti, behet, behat BrugschDict. v. 438 DümichenGeschichte 167 f. WendelAltäg. Bau- u. Edelsteine (1888) 77 f.; ᵐ5 has σμαραγδίτης), Esther 1:6 ב וְסֹחָ֑רֶת׳ִרצֲפַת וְדַר וָֿשֵׁשׁ עַל upon a pavement of porphyry and marble, etc.