It is believed that an opportunity to see, touch and worship this Parad Shivalingam is accredited to one's holy and good deeds done in the previous and present life.
In Hindu scriptures mercury is regarded as the best of all metals. The following it the purport of a sloka from Rasyog Chintamani:
"Sphatik is better than paashan, padmaraaj than sphatik, Kashmir jewel, pushparaaj, i.e., lahasunia than Kashmir jewel, panna than lahasunia, neelam than panna, godanti or gomed, mauktik than vidrum, silver than diamond, gold than silver, diamond than gold and parad (mercury) is yet better than diamond."
Therefore a 'lingam' (phallus) of Lord Shiva made of the best of all the metals should without doubt defy any parallel.
Why Mercury Shivalingam?
This analogy of mercury with the human mind is found in Tantra literature: All the metals and sub-metals send out waves. Mercury is an unstable metals just as man's mind is the most wavering. When mercury is stabilized, its waves solidify. This process causes effect on the mind. If one meditates beside a parad Shivalinga, the mind naturally gets concentrated. Therefore, a solidified form of mercury is of great significance because it is extremely helpful in concentrating the mind.
The founder and head of Siddha Ashram is Acharya Mahamandaleshwara Swami Nardanand Paramahansa Maharaj. The focus of the sadhana (spiritual practices) taught by the Swami is Kundalini Shaktipat Yoga Meditation, including practices of Yoga, Vedanta and Tantra.