What is "manikkavacakar"

Maanikavasagar was a 9th-century Tamil poet who wrote Tiruvasakam, a book of Shaiva hymns. Maanikavasakar was one of the main authors of Saivite Tirumurai: his work forms one volume of the Tirumurai, the key religious text of Tamil Shaiva Siddhanta. A minister to the Pandya king Varagunavarman II (c. 862 C.E. – 885 C.E.) (also called Arimarthana Pandiyan), he lived in Madurai. His work is a poetic expression of the joy of God-experience, the anguish of being separated from God. Although he is a prominent saint in Southern India, he is not counted among the sixty-three nayanars.