Rock Of The Month For 2009-10-01

This rock was submitted by Salvatore M. from Guilherano-Granges, FRANCE, EU. Salvatore tells us that this rock is from the Jurassic superior layer of the Montagne de Crussol (Crussol Mountain). The black and light splotches on the rock are lichen. The spectrum of the host rock shows that the composition of this rock is limestone (CaCO3, or calcium carbonate) because of the primary spectral features at ~1500, 890, and 350 wavenumbers. The additional spectral features between those primary features tell us that the surface of the rock has a fine powder of calcium carbonate on the surface that is scattering some energy. Limestone is a sedimentary rock that forms at the bottom of an ocean. Plate tectonics (or the movement of the Earth's crustal plates) have caused this once-submerged deposit to be uplifted into a mountain belt. Slow, steady force on geologic timescales can cause amazing changes! But the pressures applied to uplifting this limestone into a mountain belt were not high enough to convert this limestone to marble. The rock's graininess and porosity still would classify this as a limestone. - Melissa Lane, PhD

Thanks for sending in such a cool rock!

Check out our previous rocks of the month: