Weather authorities said the powerful cyclone had weakened into a depression after devastating regional coastlines the previous day, killing at least 16 and cutting power to millions in parts of eastern India and neighboring Bangladesh.
Bitter weather was holding up rescue efforts in Melthum, the site of the quarry outside the state capital of Aizawl, a state disaster management official said.
"There have been incessant rains in the wake of cyclone Remal, which led to the quarry collapse," the official told Reuters, speaking on condition of anonymity.
There were no immediate details of the number trapped.
The heavy rain in Mizoram, which borders Bangladesh, also unleashed landslides in the region.
Authorities in India's eastern state of West Bengal were working to restore electricity lines in the worst-affected areas, after Remal stripped power lines and uprooted trees.
It is the first of the frequent storms expected to pound the low-lying coasts of the South Asian neighbors this year as climate change drives up surface temperatures at sea.