I'll have to cut this one!

This rock appears to be a type of banded iron formation (BIF) or possibly a type of jasper with iron inclusions. Here's why:

Color and Texture: The rock has a mix of red, brown, and black colors, which are typical of iron-rich rocks. The glossy appearance suggests it might have been polished or naturally has a vitreous luster.
Banding: There are visible bands or layers in the rock. Banded iron formations are characterized by alternating layers of iron oxides (which can give the red and brown hues) and silica (often appearing as lighter bands).
Iron Inclusions: The dark patches could be hematite or magnetite, common minerals in iron-rich formations. Jasper can also contain iron inclusions, leading to similar coloration.
Hardness: Both BIFs and jasper are relatively hard, which might explain why this rock appears to hold a good polish.