Don't use toxic chemicals with a ultrasonic cleaner, as particals of the chemicals will become airborne.
If you do use a fume hood and make sure the fumes are directed to a safe area.
Back when i ran a high grade mine in Allegheny Calif we ran into high grade pockets and all of them had low grade ore pockets around them, and we ran that through a mill to recover the fine gold.
In many pocket mines they only mined the high grade and left tons of low grade ore in the mines and dumps
