Autonomic Basalt appears in Halls 1 and 2 of the Steamy Bathhouse within the Midnight Channel. When defeated, it may drop Powered Iron. Selling 6 Powered Iron at Daidara will unlock the Bastard Sword for the protagonist.
Autonomic Basalts have a very high damage reduction of Physical attacks used on them. Elemental spells should be used to do damage, with Wind spells being priority.
In Golden, Autonomic Basalt appears in Halls 1 through 4 of the Steamy Bathhouse within the Midnight Channel. It also drops Smoky Quartz that can be exchanged at Shiroku Pub.
Autonomic Basalt appears in Area 2 and Area 3 of the second Theater, Junessic Land. It attacks with Physical skills. When defeated, it may drop Basalt Crystal and Basalt Ore. Basalt Crystal is used to create the Silver Dagger for the P5 hero, the Long Stick for the P3P heroine, Verdure Greaves for Chie, and the Baby Arquebus for Naoto. Basalt Ore is used to create the Heavy Mace for Ryuji, the Bardiche for Haru, the Titanium Club for the P4 hero and Junpei, the Steel Plate for Kanji, and the Utility Apron female armor.