Also see definition of "Amber" in Word Study
Study Dictionary
Amber
Amber [EBD]
(Ezek. 1:4, 27; 8:2. Heb., hashmal, rendered by the LXX. elektron, and by the Vulgate electrum), a metal compounded of silver and gold. Some translate the word by "polished brass," others "fine brass," as in Rev. 1:15; 2:18. It was probably the mixture now called electrum. The word has no connection, however, with what is now called amber, which is a gummy substance, reckoned as belonging to the mineral kingdom though of vegetable origin, a fossil resin.
AMBER [SMITH]
(Heb. chasmal) occurs only in (Ezekiel 1:4,27; 8:2) It is usually supposed that the Hebrew word chasmal (denotes a metal) and not the fossil resin called amber .Also see definition of "Amber" in Word Study