Topic 11: Earth Materials – Minerals, Rocks, and Mineral Resources The solid surface of the Earth that we live on is called the ____Lithosphere_____ and is made up of
_Rocks_ and _Minerals.
Minerals have characteristic __Physical____ and _Chemical____ properties. List some of seven of these properties. 1. Color; 2. Streak; 3. Luster; 4. Hardness; 5. Density; 6. Cleavage; and 7. Crystal structure.
Define mineral: A naturally occurring, inorganic, crystalline solid having a definite chemical composition.
What does it mean to be inorganic? Not been made of or by life forms.
What does crystalline mean? An orderly atomic arrangement
All minerals are rocks, but not all rocks made of minerals. Explain how a rock could not be made of minerals. Some rocks are made of organic materials. Or a rock could be made of glass, which is not crystalline.
Figure 11-2., shows that only a small number of minerals are commonly found in rocks. 90% of Earth’s crust by weight is composed of eight minerals or groups of minerals all known as Silicates____. Because they contain the element silicon and oxygen.
Another phrase for crystal structure is atomic arrangement.
What is the name of the structural unit of silicates? Tetrahedron
Minerals can form in two ways:
#1. Inorganic crystallization
Topic 11: Earth Materials – Minerals, Rocks, and Mineral Resources The mineral corundum can have a ruby red color, sapphire blue color or be colorless. Explain how?
Why is color often not useful for mineral identification?
Many minerals have the same color. In addition, the color of many minerals varies due to impurities, and many minerals are clear or colorless when pure.
Define streak: the color of finely crushed residue or powder of a mineral
Why is streak more reliable than color for mineral identification? Streak is more consistent than color because the impurities don’t show as much when the mineral is ground up into a powder.
What are the two broad groups of mineral luster?
Metallic and Non-metallic
Define hardness: The resistance to scratching.
How does Moh’s scale work? The scale is based on a 1 – 10 rating system with 1 being the softest and 10 being the hardest.
Define mineral cleavage: the tendency to break along zones of weakness and form smooth to semi-smooth parallel sides, or surfaces.
If a mineral doesn’t cleave when it breaks, it will demonstrate uneven breaking or fracture.
What is conchodial fracture? What common silicate mineral shows conchodial fracture? Conchodial
fracture is when a mineral breaks into circular patterns. Quartz shows conchodial fracture.
Which minerals or rocks react with acid? What kind of reaction occurs? Calcite or Dolomite – Limestone and Marble. Bubbles with acid – effervescence.
Topic 11: Earth Materials – Minerals, Rocks, and Mineral Resources Rocks can be made of a single mineral or can be mixtures of _minerals, organic materials, glasses, and fragments of other rocks.
The three categories of rocks are IGNEOUS, SEDIMENTARY, & METAMORPHIC.
Rocks are distinguished and identified by their COMPOSITION and TEXTURE.
Define texture (as it relates to rocks): GRAIN SIZE or CRYSTAL SIZE
How do sedimentary rocks form? ACCUMULATION OF SEDIMENTS.
Define clasts: SOLID SEDIMENT – Broken bits of rock
Why do most sedimentary rocks form at the bottom of lakes, seas, and oceans? Most sedimentary rocks form under large bodies of water, such as lakes, seas, and oceans, where
the sediments are usually deposited in horizontal layers.
List the four methods of formation for sedimentary rocks: CEMENTATION, COMPACTION,
CHEMICAL ACTION, ORGANIC PROCESSES.
What three minerals are commonly the “glue” that cements clastic sedimentary rocks together?
CALCITE, QUARTZ, & HEMATITE
Shale and coal are formed solely by COMPACTION. But, most clastic sedimentary rocks form from a combination of COMPACTION and CEMENTATION.
Evaporites are formed by the process PRECIPITATION.
Define Organic: FROM LIFE PROCESSES
Why are the clasts that make up sedimentary rocks often rounded? THEY’VE BEEN
TRANSPORTED BY WATER.
Define Fossil: EVIDENCE OF PAST LIFE
What is the difference between Conglomerate and Breccia?
CONGLOMERATES – ROUNDED PARTICLES
BRECCIA – ANGULAR PARTICLES
Topic 11: Earth Materials – Minerals, Rocks, and Mineral Resources
Bioclastic limestone is composed of CaCO3, so it will BUBBLE with acid.
Rocks that form when natural molten rock-forming material cools and turns into a solid are
IGNEOUS. This process is known as Solidification.
Define magma: MOLTEN ROCK – PARTIALLY MELTED
How is lava different from magma? LAVA IS MOLTEN MATERIAL AT OR ABOVE THE EARTH’S SURFACE. MAGMA IS MOLTEN MATERIAL BELOW THE EARTH’S SURFACE.
When magma solidifies it forms rocks called INTRUSIVE (PLUTONIC).
Batholith, stock, laccolith, sill, and dike are all types of INTRUSIONS.
When lava solidifies on or above Earth’s solid surface, the result is EXTRUSIVE (VOLCANIC).
When does crystallization occur? WHEN MOLTEN MATERIAL COOLS
Why is glass non-crystalline? THE MOLTEN MATERIAL COOLS SO FAST, THE ATOMS DO NOT ARRANGE THEMSELVES INTO A REPEATING PATTERN.
What conditions are necessary for a rock to have large coarse crystals easily visible to the human eye?
(Think time frame) VERY SLOW COOLING
If lava cools quickly, fine-grained rocks form. Fine-grained rocks have SMALL crystals that are not easily seen with the unaided human eye. If the cooling is very fast a GLASSY rock with no or few mineral crystals form.
What controls the texture of igneous rocks? THE RATE OF COOLING.
If a rock has rounded openings that were caused by lava solidifying around trapped expanding gases
it has a VESSICULAR texture.
Identification of igneous rocks is based on what two things? MINERAL COMPOSITION & TEXTURE
Rocks that form from changes in previously existing rocks due to HEAT, PRESSURE, and/or
MINERAL FLUIDS without weathering or melting are Metamorphic rocks.
Topic 11: Earth Materials – Minerals, Rocks, and Mineral Resources
Metamorphism usually occurs where? WITHIN THE LITHOSPHERE (not at the surface)
Layering of mineral crystals is called FOLIATION. (This is an important term!)
What is recrystallization? The process of increasing the size of the mineral crystals or rock clasts
and/or changing the mineral composition without melting.
When older rocks come in contact with the magma of an intrusion or lava of an extrusion, the heat
and mineral fluids of the liquid rock alter the older rock in a process called CONTACT
Regional Metamorphism occurs in the lithosphere when PLATES COLLIDE.
Look at figure 11-14 on p.201.
Sandstone is the parent rock of QUARTZITE. Dolostone is the parent rock of MARBLE
Limestone is the parent rock of MARBLE.
Shale is the parent rock of SLATE, PHYLLITE, SCHIST, & GNEISS
Siltstone is the parent rock of HORNFELS.
Metamorphic rocks are classified and identified based on MINERAL COMPOSTION and TEXTURE.
Environment of Rock Formation
Salt beds in western NYS lead to the inference that … THERE WAS A LARGE AREA OF SALTY WATER IN THE PAST THAT HAS EVAPORATED
The distorted rock structures of the metamorphic rocks exposed in the Adirondacks indicate that … THE AREA HAS EXPERIENCED ON OR MORE PERIODS OF MOUNTAIN BUILDING –
Large silicate mineral crystals in an igneous rock indicate … SLOW COOLING