earthstory reblogged
oh Nice
(this is taken from moi textbook The Earth Through TIme by Harold L. Levin and David T. King Jr)
earthstory reblogged
NWA 10669 Meteorite Thin Section
Recommended print size at 300 ppi =
Check out all the little round chondrules
Views of a “Chondritic Meteorite” in thin section. This is a meteorite that was polished to only about 0.03 millimeters thick, thin enough that light can travel through the rocks. It is then put on a polarizing microscope and polarized light is sent through it. That gives you a chance to see some of the minerals and textures, but there is a second step here. A geologists microscope will have a second polarizer above the sample. That second polarizer can be rotated so that only light that had its direction changed by passing through the mineral reaches the eye of the viewer. This produces an effect called Birefringence, the colors seen in these grains. Birefringence colors can be used along with mineral textures to identify rock types.
This video shows the upper polarizer being rotated, so the light goes from singly-polarized to doubly polarized and colors appear as they do it.
The spherical blobs in this sample are the chondrules. They are thought to have been blobs of rapidly melted, rapidly cooled rock that floated out in space. Eventually they were assembled into rocks on some of the early asteroids.