These green crystals are olivine (aka peridot). If you were to choose a representative mineral for Earth, this would be a good choice since olivine is the most abundant mineral in Earth's upper mantle. Over 50% of the planet's subsurface mineral makeup is olivine. In fact, based on its ability to contain water, it is estimated that more water may be dissolved in olivine of the mantle than is contained in Earth's oceans.
