3. (4 pts) Your instructor has presented you with a yery dark gray colored rock (nearly black), and you immediately notice its surface is covered with round holes (a bit like a block of Swiss cheese, except for the dark gray color). It is sparkly, so you know it is made of crystals, but they are much too small for you to recogmize what mineral (or minerals) the rock is made of. It is not noticeably layered, and water just sits on the surface of the rock, and doesn't soak in. Is this rock most likely igneous, sedimentary or metamorphie? What evidence supports your conclusion? What is the significance, if any, of it being made of tiny, almost microscopic crystals? Finally, what is the significance of the round holes?.