Usage: 3 forms in 3 verses
Form Translated As     In Verse(s)
ασφάλτω asphalt LXX.Gen.6.14
ασφάλτου of asphalt LXX.Gen.14.10
άσφαλτοσ asphalt LXX.Gen.11.3

Liddell-Scott-Jones

ἄσφαλτος (asphaltos) tar G:N-M

ἄσφαλτος,

(also , [Refs 2nd c.AD+], asphalt, bitumen, [Refs 5th c.BC+]:— also ἄσφαλτον, τό, [Refs 5th c.BC+]

__II a kind of petroleum, [Refs 1st c.AD+]
__III pitch, [LXX+1st c.AD+]

LSJ Scripture Refs: LXX.Gen.6.14