Anandakanda 1.23.98

1.23.98

śoṣayedvālukāyantre dinaṃ mandāgninā pacet /
rasabhasma bhaveddivyaṃ rugjarāmaraṇāpaham //

dry it, and cook it in a sand apparatus for a day over a mild fire.
It becomes a divine mercury calx, dispelling sickness, senescence, and death.