Marble substance material, part of the Marbleous Pack, available @ http://cbr.sh/jmx6z Completely procedural seamless texture with resolution up to 4k, with controls for: Cracks presence Veins color Stone color and Veins direction. Use Radnomize for infinite variations.

If you don't own any of Allegorithmics products use their free Subastance Player application for extracting to any file format that you desire.