Teak or walnut?  

Leif is Correct again.

Good thing I didn't bet on this game.

The detailed picture clearly displays one of Teak's idiosyncratic grain patterns.

Yeah, that was the image that finally gave the answer. It was very hard to tell before seeing that photo.

I was hoping that this picture could be a clue but I wasn

The first couple pictures, above, make me want to say mahogany......but it is teak. Probably really dirty, or worse, stained at some point. As stated, the picture of the corner does seal it for 3 reasons:

1. the top veneer is cleaner, and in the correct color range and grain for teak

2. The checkered ray-fleck on the vertical, only occurs in a handful of furniture woods (teak, beech, maple, cherry, birch, mahogany, ash, and a few others), very few with coarse grain like this teak and ash. Oak's medulary rays are more globular.

3. The horizontal edge displays a grain pattern that I have only seen in teak.

I probably know more about photography than about wood species, that's why I think the color is not represented correctly in any of these pictures. Hope it has not been stained though.