The miners were collecting stones in the jade-rich Hpakant area of Kachin state when the "muddy wave" crashed onto them, following heavy rain, the fire service department said in a Facebook post.
“Now we recovered more than 100 bodies,” Tar Lin Maung, a local official with the information ministry, told Reuters by phone, “Other bodies are in the mud. The numbers are going to rise.”
Deadly landslides and other accidents are common in the poorly regulated mines of Hpakant.
Media have reported scores of people killed in the area in recent years, many of them freelance "jade pickers" who scour tailings - the residue from mining - for stones that have been missed by larger operators.
Maung Khaing, a 38-year-old miner from the area who witnessed the accident, said he spotted a towering pile of waste that looked on the verge of collapse and was about to take a picture when people began shouting ‘run, run!’.
“Within a minute, all the people at the bottom (of the hill) just disappeared…,” he told Reuters by phone. “I feel empty in my heart. I still have goose bumps… There were people stuck in the mud shouting for help but no one could help them.”
The government of Nobel laureate Aung San Suu Kyi pledged to clean up the industry when it took power in 2016, but activists say little has changed.
Official sales of jade in Myanmar were worth 671 million euros ($750.04 million) in 2016-17, according to data published by the government as part of an Extractive Industries Transparency Initiative.
But experts believe the true value of the industry, which mainly exports to China, is much larger.