Anandakanda 2.5.47

2.5.47

saṃpeṣya gālayedvastre satyaṃ vāritaraṃ bhavet /
kāntaṃ tīkṣṇaṃ ca muṇḍaṃ ca nirutthaṃ jāyate mṛtam //

Grinding it thoroughly, one should sift it through cloth; truly it becomes water-floating; / loadstone, cast iron, and wrought iron become dead and incapable of reviving.