Anandakanda 1.2.137

1.2.137

rasaliṅgaṃ dvidhā proktaṃ sakalaṃ niṣkalaṃ priye /
pūrvoktaṃ sakalaṃ liṅgaṃ niṣkalaṃ kevalo rasaḥ //

The mercury-liṅga is said to be of two kinds, O dear one: composite and uncompounded.
The previously described is the composite liṅga; the uncompounded is mercury alone.