This assignment is simple (well, simple to describe; perhaps not so simple to complete). You are to make thin sections of two unrelated rocks in room 218 that do not currently have thin sections. You will then identify all major and minor minerals present in the rock, and turn in a description of each thin section.

The descriptions should contain the following:

• detailed descriptions of each mineral, including how you know the identity of each mineral, and estimate of chemical composition, if possible
• estimates of modal percent of each mineral in the rock
• descriptions of any interesting larger-scale textures, or relationships between minerals
• well-labeled sketches or photomicrographs, where useful for illustrating textures

We may have a "show-and-tell" day near the end of the quarter, where we discuss the thin sections.

Each rock will be worth 50 points. You will not be graded on the quality of the thin section you produce (although poorly-made thin sections will be difficult to work with or identify minerals in).