VIDEO CAMP SCRIPTS – GS 106: GEOLOGY
Gretchen Gebhardt
Video 3: Sedimentary & Metamorphic Rock Identification
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What you hear
Welcome to lab prep video 3 – Sed & Met Rock identification! In lab you will have a set of rocks, testing supplies and the lab documents you have printed out (don’t forget the Identification chart!) to aid in the identification process. What I would like to do in this video, is to run through the basic properties while showing you some examples (this correlates nicely with the ID charts!) You will be recording your observations on the blank ID you have printed out.
Sedimentary
Step 1: Texture – coarse or fine?
Can you see or feel the mineral grains? If so – coarse grained. No? fine!
Step 2: Harder or softer than glass
Same test as for minerals! Use glass plate carefully!
Step 3: Texture (size, shape, arrangement)
Sizes range from mud – silt – sand – gravel – pebble – cobble – boulder
Shape: anguler or rounded or sub
Arrangement – random or layered?
Step 4: Mineral Composition
Quartz/Feldspar/rock fragments/Halite/Calcite/Clay
Acid & glass test
Step 5: Detrital/Chemical/Biochemical
Rocks or minerals glued together, precipitated out of water chemically or created through biologic activity (fossils!)
What you see
Gretchen Talking
Zoom in on examples coarse & fine samples while Gretchen points them out as they are described
Zoom in on examples of hard & soft rocks while Gretchen points them out as they are described
Zoom in on examples of various grain sizes, shape and arrangement as Gretchen describes each.
Zoom in on examples of each type of mineral in a rock sample
Zoom in on examples of each as Gretchen describes each category.
What you hear
Metamorphic
Step 1: Texture – Foliation & Banding
Foliation refers to the alignment of minerals parallel to one another in a sample. Usually visible by looking for cleavage faces of minerals in the sample that all reflect the light at a similar time.
Banding = minerals separate into different color bands. Looks like zebra pattern
Step 2: Texture - size
Coarse vs. Fine (can you see the mineral grains or not?)
Step 3: Mineral Composition & Hardness
Harder or softer than glass? (same process as with minerals) Qtz, Kspar, Amp, Plag, etc.
If you can’t see the mineral, don’t report it!
Remember from last week what minerals look like? (Qtz glassy, micas – flat sheets or stop sign, HB/Amp – rectangle, feldsp – pink dull white) Calcite – acid Rx
Step 4: Parent Rock
Use chart! This is the rock it was before metamorphosed. (Usually similar in composition)
Metamorphic Grade & Parent Rocks
First you will organize the box into the order of metamorphic grade, and then add the correct parent rocks for each metamorphic rock. Either show me in class or take a photo for me and include it in your lab submission.
Use the chart to identify your samples. Email me if you have questions!
What you see
Zoom in on examples of minerals while Gretchen points them out as they are described
Zoom in on samples showing fine and coarse grained metamorphic rocks
Zoom in on rocks with minerals listed as Gretchen points them out.
Zoom in on chart & example of metamorphic rock & parent
Zoom in on random rock boxes for this part & diagram drawn on board
Gretchen Talking
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