Here's something only a stoner could think of. The folks at Shwood, the Portland-based makers of wooden sunglasses, have taken a chip off the old block and made the first slate-framed sunnies, combined with a birch and hand-poured pewter. Two wayfarer styles come in either black or white slate. These aren't farmed out to a manufacturer, but crafted in Shwood's own workshop, where they also do all the veneering and lens-cutting, so you'll have to forgive them for limiting the stone sunglasses to 200 pairs.
$325 at Shwood