A.T. Robertson Commentary Revelation 18:19

"And they cast dust on their heads, and cried, weeping and mourning, saying, Woe, woe, the great city, wherein all that had their ships in the sea were made rich by reason of her costliness! for in one hour is she made desolate." — Revelation 18:19 (ASV)

They cast dust (εβαλον χουν). Second aorist active of βαλλω. Χους is old word (from χεω to pour) for heap of earth, dust, in N.T. only here and Mr 6:11. Cf. Ezekiel 27:30; Luke 10:13. This is the dirge of the sea-folk (cf. verses 10,16).

By reason of her costliness (εκ της τιμιοτητος αυτης). Occasionally in later literary Greek, though here only in N.T. and not in LXX. The same use of τιμη appears in 1 Peter 2:7. Common in the papyri as a title like "Your Honor" (Moulton and Milligan's Vocabulary).