The word(s) "dark" appears 33 time(s) in 31 verse(s) in Quran in Muhammad Pickthal translation.

(11) And He it is Who hath set for you the stars that ye may guide your course by them amid the darkness of the land and the sea. We have detailed Our revelations for a people who have knowledge.

(12) Is he who was dead and We have raised him unto life, and set for him a light wherein he walketh among men, as him whose similitude is in utter darkness whence he cannot emerge? Thus is their conduct made fairseeming for the disbelievers.

(13) And those who earn ill-deeds, (for them) requital of each ill-deed by the like thereof; and ignominy overtaketh them - They have no protector from Allah - as if their faces had been covered with a cloak of darkest night. Such are rightful owners of the Fire; they will abide therein.

(14) Say (O Muhammad): Who is Lord of the heavens and the earth? Say: Allah. Say: Take ye then (others) beside Him for protectors, which, even for themselves, have neither benefit nor hurt? Say: Is the blind man equal to the seer, or is darkness equal to light? Or assign they unto Allah partners who created the like of His creation so that the creation (which they made and His creation) seemed alike to them? Say: Allah is the Creator of all things, and He is the One, the Almighty.

(15) Alif. Lam. Ra. (This is) a Scripture which We have revealed unto thee (Muhammad) that thereby thou mayst bring forth mankind from darkness unto light, by the permission of their Lord, unto the path of the Mighty, the Owner of Praise,

(16) We verily sent Moses with Our revelations, saying: Bring thy people forth from darkness unto light. And remind them of the days of Allah. Lo! therein are revelations for each steadfast, thankful (heart).

(17) When if one of them receiveth tidings of the birth of a female, his face remaineth darkened, and he is wroth inwardly.

(18) And We appoint the night and the day two portents. Then We make dark the portent of the night, and We make the portent of the day sight-giving, that ye may seek bounty from your Lord, and that ye may know the computation of the years, and the reckoning; and everything have We expounded with a clear expounding.

(19) Establish worship at the going down of the sun until the dark of night, and (the recital of) the Qur'an at dawn. Lo! (the recital of) the Qur'an at dawn is ever witnessed.

(20) And (mention) Dhu'n-Nun, when he went off in anger and deemed that We had no power over him, but he cried out in the darkness, saying: There is no Allah save Thee. Be Thou Glorified! Lo! I have been a wrong-doer.