Contrary to most translations, the mountain never crumbled to dust. Mount Sinai is still in existence in the Sinai Peninsula. The most easily accessible reference is Tafhimul Qur'an by Maududi, Urdu Volume 2, page 76 foot-note along with a topographical map. In English you may want to check the explanation of Al-A'raaf 7:143. Inspite of giving all that info, Mullah Maududi, maintains that the mountain did crumble to dust. What a glaring example of blind following!
7:143 When Moses arrived at the appointed time, and his Lord spoke to him, Moses said, "My Lord! Give me the power to better perceive You." His Lord said, "You will not perceive Me unless you look pensively at the mountain. If it remains firm in its place, then shall you perceive Me." (You will realize that even a single mountain is made of countless particles that were scattered as dust and it is your Lord Who has made it stand firm.) Thus did his Lord choose for the mountain to be a manifestation of His Glory. Moses thought of the mountain as dust and was stunned! When he recovered his senses, he said, "Infinite are You in Your Glory! I turn to you repentant and I am among the foremost believers.”
Wassalam,
SA
SA