2.25x4.75" black onyx base holds 5.75x6.75x1" thick sculpture of a salt water fish in motion. Fish has been carved out of a solid piece of rhyolite, a volcanic rock. Due to high silica content and low iron/magnesium contents, rhyolite melts are highly polymerized and form highly viscous lavas. Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. Slower cooling forms microscopic crystals in the lava and results in textures such as in the sculpture we are offering. The effect in this piece is known as dendritic, from the Greek that means "tree." Given the black leaf-like formations of maganese throughout the piece, it's easy to see why. This piece was also carved by the artist Rodin Lee, the same artist who sculpted the previous item #2973. Exc.