HW4: Rock ReportSergiosubiranaj
Rock Report Name:
This is an individual homework activity on rocks and minerals. Each student must produce a one-page research report on
an assigned rock. You can sign up for a rock on Teams (same way you signed up for a country); students who haven’t
chosen one by Wednesday, 2/10 will have them assigned for them by me. The rocks include igneous, sedimentary, and
metamorphic rocks. This homework is worth 100 points.
Do not start this homework until you’ve finished all the lessons through M4.8. It is due on Wednesday, February 17th at
Your rock report must describe the chemistry and mineralogy of your rock and its included minerals, and explain where
and how the rock forms. But this part is very important:
You must underline and define any words or terms you use that are not part of the vocabulary learned in this
class. If we’ve used a term in this class then you don’t need to define it. For example, it is OK to simply say that
granite has a felsic composition, because you have learned the term felsic in this class. It is not OK to say that
granite may have a rapakivi texture with large round orthoclase crystals because your readings haven’t
included the terms “rapakivi” or “orthoclase”. If you need to use these terms you must define them in your own
In fact, everything you write must be in your own words! Plagiarism will result in a grade of FF for the class.
Here’s an example for the rock Granite:
Granite is an igneous rock with a phaneritic texture. It has a felsic composition. The most common minerals in
granite are quartz, potassium feldspar (sometimes called orthoclase), plagioclase feldspar, biotite and
amphibole. Quartz is a framework silicate with the composition SiO2. Potassium feldspar or orthoclase is a
framework silicate with the formula KAlSi3O8. Plagioclase feldspar is a framework silicate with a composition
between NaAlSi3O8 and CaAl2Si2O8. In granite, the plagioclase tends to be rich in Na. Biotite is a trioctahedral
layer-silicate mica rich in Fe and Mg. Amphibole is a double-chain silicate, and the variety common in granite is
called hornblende, which is a dark-colored mineral rich in Na, Fe, Mg, and Al. Some granites also contain
muscovite, which is a dioctahedral layer-silicate mica rich in Al.
Granites are common in continental arcs formed above subduction zones. They form when felsic magma cools
slowly underground. Granites often form large batholith or stock bodies like the Sierra Nevada Batholith, or
the Idaho Batholith.
References: [to be provided]
In this example the italicized words are ones you’ve learned from the readings and the underlined words are new. You
don’t have to italicize the familiar words, but you do have to underline and define the new words that you’ve learned.
For each mineral in your rock, you should describe how it is classified, and for silicates you should describe both its
chemistry and structure (e.g., “plagioclase feldspar is a framework silicate with a composition between NaAlSi3O8 and
CaAl2Si2O8. In granite, the plagioclase tends to be rich in Na.”)
Your rock report doesn’t need to be much longer than this example and should include references you used in your
research. Your report must include a description of the structure and chemistry of any minerals found in your rock.
Type your report in a word-processing program and save as a file. You will copy and paste the report into a Canvas Quiz
that will serve as a repository of your homework.
These are your choices:
Banded iron formation