Recently found this rock at a yard sale, would love to know what it is!

Only one side is semi-polished, but every facet including the rough ones seems laced with the most vivid, iridescent blue-purple-green I've ever seen! The rest of it is just rough, brown, and kind of a yellowish-tan. The polished side makes me think of cooled lava, so maybe that's what caused the glass-like cracks in there? I dunno😅 I'm just very curious.

The lady I bought it from collected her rocks from Australia, so if that helps identify it, that's what I know🥰