User Summary: The Lava River Pack is made of "Dwarvenite" and expands the Cavern Base Set. This pack was initially available as an Add-On pack to the Caverns Kickstarter. The set is painted black with yellow and red lava river effects throughout. The Lava River Pack comes complete with these 15 pieces: (2) Archway (4 inch) (6) Bank, Concave (4) Bank, Convex (2) Bank, Diagonal (12) Bank, Straight (4) Open Lava (2x2)