Examine at least 5-6 slides of the olivine slides and try to identify the minerals and list the optical properties that you observe in olivine: Also make sure that you are examining Forsterite, Fayalite or olivine ([Mg,Fe]2SiO4 ) use your books to tell the difference among these minerals.
Olivines have isolated SiO4 groups in and structure and so are known as Nesosilicates. Olivine is exceedingly abundant as a rock-forming mineral in subsilicic igneous rocks. Forsterite is found in limestone of contact metamorphic zones. Fayalite is found in granite pegmatite, and in rhyolitic obsidians.
Examine the olivine slides and answer the following questions.
1. List 5 optical properties that you observe in olivines.
a.
b.
c.
d.
e.
2. How can you tell Fayalite from Forsterite?