Shiva Purana
आदाय शंखं साधारमस्त्रमन्त्रेण भस्मना ॥ शोध्य तत्पुरतस्स्थाप्य चतुरस्रे समर्चिते ॥ ३३ ॥
He shall then take the conch with the pedestal and purify it with Bhasma and the Astra mantra. He shall put it before the disciple on the square and worship it.
english translation
AdAya zaMkhaM sAdhAramastramantreNa bhasmanA ॥ zodhya tatpuratassthApya caturasre samarcite ॥ 33 ॥
hk transliteration by Sanscript