PLALE. IT: 
MICROSCOPIC STRUCTURE OF MINERALS AND ROCKS. 

1. Plagioclase showing Albite-twinning. Gabbro. Nicols crossed. 
2. Plagioclase showing Albite- and Pericline-twinning. Diorite. Nicols crossed. 
3. Twinned crystal of Sanidine (Orthoclase) in pseudo-spherulitic groundmass. Rhyolite. Nicols 
crossed, 
4. Crystals of Sanidine (Orthoclase) showing Carlsbad-twinning and fluxional arrangement. Trachyte. 
Nicols crossed. 
