Brecciated Jasper!

The rock in the image appears to be a type of jasper, specifically a brecciated jasper. Jasper is a variety of chalcedony, which is a microcrystalline form of quartz (SiO₂), often prized for its vibrant colors and patterns. Brecciated jasper is characterized by its fragmented, angular appearance, where the rock has been naturally broken and then recemented together by silica-rich fluids, often resulting in a mix of colors like the reds, browns, and blacks seen here. The red hues are likely due to iron oxide (hematite) inclusions, while the darker areas could be from other mineral impurities or organic material.
The polished, glossy surface suggests that this rock has been tumbled or naturally smoothed, which is common for jasper found in riverbeds or as pebbles. The intricate, veined patterns and the mix of colors are typical of brecciated jasper, which often forms in environments where tectonic activity or other geological processes have fractured the original rock, allowing silica to infiltrate and bind the pieces back together.