Pressurized limestone underneath the Earth’s crust allows marble to form. Impurities in the limestone during this process give marble its rich palette of beautiful colors and appearance depending on the infringing minerals. Such impurities form bands, streaks and clouds. Black and grayish shades are due to graphite; pinks, reds are mainly due to the presence of manganese oxides or hematite. Marble is a lot softer than its counterparts. Compared to granite, it is more porous, which is why it’s mostly used for bathrooms and fireplaces rather than your kitchen.