Anandakanda 1.26.127

1.26.127

bhāgasya pūrayitrībhir anyābhir avakuṇṭhayet /
bhāṇḍavaktraṃ maṇikayā sandhiṃ limpenmṛdā pacet //

and one should shroud it with other [sands] that fill the [remaining] part.
[One should cover] the mouth of the vessel with a shallow bowl, smear the joint with clay, and cook [it]