I've watched nearly every episode in the Tekkit with Sips and Sjin YouTube series, and I keep seeing this particular oddly-colored block amongst the stone bricks that make up the bases of their facility buildings. I've taken a still image from their Christmas Special as an example:
The block appears to have a stone brick texture, but each of the 4 bricks in the block is a different color. I've never heard them make any mention of what this was or how they made it, and I've never come across it in the Technic item inventory. What is this? Is it an actual block you can create, or a special texture for some other block in the texture pack that they use?