I'm looking for a 16"x16" square tile that has the look of gray concrete with a bit of texture so it's not slippery that would work as indoor flooring but could also be used for an outdoor raised deck in the Pacific Northwest. We had been planing to use slate tile squares for the deck but I'd like to use the same material inside and out if possible. Is there a suitable product? Deck installation would be no grout, gaps between for drainage. We want 16" so we can use standard deck framing but the deck structure will be rebuilt also.