Anandakanda 1.23.84

1.23.84

bījaiḥ samāṃśaiḥ saṃmardyaṃ caturyāmaṃ sureśvari /
vajramūṣāgataṃ dhāmyaṃ bhasmībhavati pāradaḥ //

in equal parts it should be ground for four watches, O ruler of gods;
placed inside a vajramūṣā crucible, it must be blown; the mercury turns to calx.