EXCLUSIVE

The Estate of Matthew Mellon, the heir to the banking dynasty who died last month on his way to rehab, wants to sell one of his big assets before it crashes and burns -- cryptocurrency.

The Estate -- estimated worth $100 million -- consists almost entirely of cryptocurrency. According to legal docs, the Estate is deeply concerned about the volatility of the digital money, noting since Matthew's death it's fluctuated by up to 30% of its value.

The Estate wants to unload the currency STAT ... faster than the normal course of action in probate court.

It's clear from the legal docs, obtained by TMZ, the Estate has little faith in the long-term viability of cryptocurrency, making it clear they believe the trajectory of the digital money is a downward spiral.

The 54-year-old heir had a history of drug abuse. In 2016 he was reportedly spending $100k a month and taking 80 OxyContin pills a day.