Download Looking At Your Rock Collection (student journal)

Looking At Your Rock Collection (student journal)
Materials
journal
drawing supplies
magnifiers
Digital camera
Steps
1. Examine each rock carefully. If possible, draw or photograph it at close range.
2. See if you can locate any of the following special features.
a. Crystals, and if so, how big are they?
A collection of granite.
- Groupings of specific minerals. Granite – the continental rock you are
MOST likely to find – is made of three minerals - feldspar, mica and
quartz.
- Flat planes of crystal that can be peeled off. (e.g. mica)
- Empty small geometric holes where crystals have fallen out of rock
- Large untwisted crystals can be from volcanic rock. (ex: gabbro)
b. grain size.
Coarse grained rock (left) and fine grained (right)
Fine grained rocks were formed quickly, while large crystal "grains" were
formed more slowly.
c. Veins of a contrasting mineral that runs into or
around a rock. (Often the vein is white, as material with lots of chalk-like
compounds like calcite dissolves easily and will pour through a rock
opening. White "icing" may be left over from a white layer of soft material
that has worn away.
c. Holes.
Smooth holes – can be fossil holes of early life such as worms or shrimp
Many rough holes –might be from gases in volcanic eruptions. This
material cooled too quickly for crystals.
d. Folds and twists. The rock has been twisted in collision.
e. Swirls – rock has been so molten it flows like syrup before it hardens.
f. Bands –Bands can occur when sediment of different composition was
laid down and hardened, or can intrude into cracks.
g. Colors
Rust stains -- from iron oxide crystals in rock cracks.
Red, purple and yellow – also from iron oxides
Black - from volcanoes, igneous like basalt.
Green - iron oxides formed in low-oxygen environment
3. Sort the rocks into 3 kinds of groupings. Make your own decisions about
which ones are the best.
4. Share your categories with the class, and then select the best categories to
share with Global Lab. Share pictures of the rock collection with GL, along with
any drawings and descriptions you can make available.
In your annotation you can also share ideas of how to display your rocks.
Homework: (Russian only) Student Text Geology 2. (Rocks, Minerals and)
Crystals