Drusy what? Quartz, cobaltocalcite, uvarovite garnet, or???
Different approaches will be required for different minerals. If it’s
quartz I’d recommend a spray with 409 followed by gentle scrubbing
with an old toothbrush after 10 minutes or so. Rinse in hot water and
dry with soft cloth to prevent spotting. Repeat as necessary. Unless
it’s a crumbly piece it won’t hurt the stone.