Answer key starts on next page

Note –

In order to decrease the amount of time to score the test, 4 of the Stations were not scored for the 2016 invitational.

Result was a total possible raw score of 77 points.

Photos of all the stations with samples are found in the google drive shared folder

2016 Division B/CBoyceville Invite

Dec. 3, 2016

Rocks and Minerals

School: ____ Key ______

Names: ______

1. sedimentary structure ______ripple marks______

water motion:current from C toward A

how you can tell:asymmetric with the steep side pointing down stream (longer side pointing upstream)

2. Name Composition

A - ____halite______NaCl______

B - ______calcite______CaCO3______

How you tell them apart:by their shapes (A is cubic, 90o, and B is slanted angles (rhomohedral)

General name of mineral property: ___cleavage_____

Optical property of sample B : ___double refraction (birefringence)____

3. Lowest grade ------ Highest Grade

__E -slate______A -phyllite______B – schist______D - gneiss____

Metamorphic texture name: ____foliated (foliation)_____

*Cause of the texture: ____the mineral grains are aligned in response to pressure______

4. Mineral names (give Letter and name):

___A – hematite______B- magnetite ______C - hematite______E - pyrite_____

[D is quartzite – meta rock]

Have in common: ___all contain Fe(iron)______

5. Sample letter and name: ___B – calcite _____

Why?: it’s a carbonate and the others are silicates

A(talc) C (plagioclase) D (quartz)

6. provide letter and name

_C conglomerate_ _E conglomerate (course sandstone)_ _A sandstone__ _B shale _

Highest energy ------ Lowest energy

Explain how you determined the order: by grain size - the larger the grain size the higher the energy (smaller the grain size the lower the energy), so they are ordered based on the size of the grains C is largest, B is smallest, E larger than A

[D is scoria]

7. Provide Letter and Name

___D – basalt______C - andesite______B - gneiss_____

Location X Location Y LocationZ

8. only the igneous rocks

Letter / Name
On or near earth surface
Deepest in crust / E / Obsidian
A / Diorite
C / granite
B / granite

[D is not igneous – conglomerate]

9.

metamorphic samples
letter - name / possible parent rock sample(s) letter(s)
B - Marble / D - limestone
E - quartzite / A - sandstone

[C is gypsum]

Texture term:___non-foliated__

10. Letter and Name

Most Mafic ------Most Felsic

______C - gabbro ______D-diorite______B-granite______

extrusive equiv: ______basalt______andesite______rhyolite______

11. mineral name: ____garnet_(almandine)______, mineral class: ___silicate___

metamorphic grade: ____medium regional (amphibolite)___

*Explain: garnet forms (is stable) at the temperature/pressure conditions described as medium regional; under lower temperature pressure conditions the garnets would not yet crystallize; and if the temperature/pressure grade when higher, any garnets that had formed would be unstable and re-crystallize into a different mineral that is stable at the higher grade conditions

12. specific gravity of A = __4.5____ math: 36/(36-28) = 36/8 = 4.5

Sample A Name ___Barite___ compositon: ____BaSO4______

Sample B Name ____Gypsum______compositon: ____CaSO4-H2O______

13.

Name / Composition / Mineral Class / Crystal System / Polymorph Name / Polymorph’s Crystal System
A / graphite / C / element / hexagonal / diamond / Cubic (isometric)
B / calcite / CaCO3 / carbonate / Hexagonal (trigonal) / Aragonite (vaterite) / Orthorhombic(pseudohexagonal)

*Product of reaction with acid: ____carbon dioxide gas______

14. Letter Mineral Name

Last to form __C__ ___quartz______

__D__ ___muscovite___

__E__ ___orthoclase___

__A__ ___biotite______

First to form __B__ ___olivine______

Named after: ___ Norman Bowen____

15. Mineral Name Gemstone name(s)

Sample A ___corundum______ruby______sapphire____

Sample B ___beryl______aquamarine______emerald_____

Name of element for Sample B ____beryllium______

*Explain colors:substitution in the crystal lattice of trace amounts of different elements (usually transition metals) causes the different colors – changes the energies of the electromagnetic fields inside the crystal lattice so different energies in the electron transitions when interacting with light

e.g. chromium that substitutes in the crystal for aluminum = pink to deep red = ruby

iron or titanium substituting for aluminum in the crystal structure has a blue color = sapphire

he pale blue color of aquamarine is attributed to Fe2+. The Fe3+ ions produce golden-yellow color, and when both Fe2+ and Fe3+ are present, the color is a darker blue

Emerald refers to green beryl, colored by trace amounts of chromium and sometimes vanadium

16. What is it ___agate____

Explain how samples got to south – central Minnesota gravel pit:

Glacial deposits– glaciers transported them there

Although agates originated in the basaltic rocks along the NorthShore,glaciers that advanced into Minnesota from the northeast, brought agate-bearing gravel into the central and southern parts of the state.

Refer to the MN bedrock geologic map on next page. Put a bold “x” on the map in all the mapped rock locations that this substance does form naturally in Minnesota.

*Explain where in Minnesota(e.g. in what other MN rock) and how the substance forms. Be as specific as possible.

Agates form in cavities in volcanic rocks (basalt) near the North Shore of Lake Superion. As mineral-rich water circulates through the cavities, silica (SiO2), or quartz, is deposited in layers along cavity walls. Eventually, the cavities completely fill with this banded variety of quartz. The color variations are due to slight mineral impurities in the water. Iron, for example, causes much of the red and orange color seen in Lake Superior agates.