| A | B |
|---|
| Crystal | a repeating pattern of atoms that forms a solid |
| Hardness | the ability of a substance to resist being scratched |
| Big Bang | Theory that states that the universe as we know it is a result of an explosion of concentrated matter and energy that continues to expand |
| Gravity | force that is thought to be primarily responsible for the formation of the galaxies after the big bang |
| Inorganic | not made of living things or from anything that was once living |
| Luster | the way in which a mineral reflects liht from its surfac e |
| Streak | after a mineral has been rubbed on a surface, the color of the powder left behind is known as |
| Malleability | ability to be hammered into thin sheets |
| Ductibility | ability to be drawn into a wire |
| Ore | minerals from which metals and nonmetals can be removed in usable amounts |
| Igneous | are formed when magma cools and hardens |
| Sedimentary | are small pieces of rocks, sediments, and other minerals, that have been cemented together |
| Metamorphic | rocks that have been changed from one type of rock into another type of rock |
| Petrologists | someone who studies about rocks |
| Rock Cycle | the continous changing of rocks into other types of rocks |
| strata | layers of sedimentary rocks |
| fault | break or crack along which rocks move |
| seisomograph | used to measure the magnitude of an earthquake |
| seismologist | someone who studies about earthquakes |
| richter scale | scale which shows earthquake magnitude |
| continental drift | theory that states that all of the present continents were once joined together and over time have drifted apart |
| magma | hot liquid rock |
| lava | magma that reaches the earth's surface |
| plate tectonics | a theory that combines the idea of continental drift and ocean foor spreading to explain the movements of the earth's crust |
| imprint | fossil formed when a thin object leaves an impression in mud and the mud hardens |
| natural selection | survival of the fittest |
| gem | a rare, beautiful mineral |
| homologous structure | structures in different organisms that are similar in structure, but may not be used for the same purpose |
| fossil | remains or evidence of a living thing |
