Charred Silica Phytolith

This is from the La Tuna fire in Los Angeles, California in 2017. The phytolith is on the right. The fiber on the left is a manmade fiber. The relief using oblique illumination shows the fiber on the right has a lower refractive index than the mounting medium, 1.485 (bright in the right). The fiber on the left has a higher refractive index (dark on the right).