Rocks and minerals- definitions and terms
Reasons why color is not useful for identifying a mineral
1) many different mineral have similar colors 2)one mineral may occur in different colors 3) some minerals change color until it is exposed to air
Rocks identified by their..
1)texture: the size shape and arrangement of the mineral grains that make up the rock 2)Composition: (crystals, sediments, fossils)
Special Properties of mineral
Acid Test, Magnetic, Taste
Sedimentary rock characteristics
Bedding or layering of sediments rounded grains, clasts, and fragments fossils- cemented sediments with visual able pores and spaces fragments from other rocks
Properties caused by Crystal Structure
Bonding, Hardness,Cleavage,
types of sedimentary rocks
Clastic (sediments) Chemical (precipitates and evaporates) Organic (biologic origin)
Igneous characteristics
Crystalline Texture Inter grown mineral grains random arrangement polyminerallic compositon glassy texture rounded gas pores or spaces
2 types of magma
Felsic and Mafic
Solid
Hard
Igneous are formed in 2 different ways
Intrusive and extrusive
Common igneous rocks
Obsidian, Pumice, Scoria
2 types of metamorphism
Regional and Contact
Felsic magma
Silica, rich... think and slow running formed light colored minerals (quartz, k-spar)
Rocks
a group of minerals bonded together
Foliation
a layered arrangement other met. rocks may be banded (colored bands
Magnetic
a magnet will be attracted to the mineral
Mineral
a naturally occurring, inorganic,crystalline (specific pattern - gives mineral strength), solid, with definite chemical composition
fossil
any evidence of former life remains, impressions, footprints
Organic sedimentary rocks
anything related to living organisms may contain fossils ex. coal, limestone
Acid Test
calcite test will react with hydrochloric acid drop of acid will fizz the acid will dissolve the calcite
Clast size
clast size can vary in size from pebbles t microscopic flakes of clay
Determine the texture of the rock
coarse,fine,porphyritic, glassy,vesicular
properties of chemical composition: Streak
color of powder
Chemical Composition
color, luster, streak
Properties caused by chemical composition
color.. color is not useful when identifying a mineral ....luster ... and streak
Streak od a nonmetallic mineral is...
colorless or white- streak is not very useful for nonmetallic minerals
Streak of a metallic mineral is..
dark and district
How to identify an igneous rock
determine the shade of the rock, light shade: (pink, red) Dark shade (green) intermediate- (between dark and light)
Properties of a mineral
determined by Chemical Composition and Crystal Structure
Sedimentary method of formation
existing rock is broken down into sediments by erosion and weathering sediments are transported to another location sediments are deposited one layer after another pressure from overlaying sediments comprises and compacts the sediments which may cause them to stick together dissolved minerals may settle into spaces between the class and cement the minerals together
Pumice
felsic lava that hardened while steam and pores were still escaping has many air holes in it sometimes it will float
Hardness
fingernail scratch (m<2.5), scratches glass plate (m>5.5)
Igneous rocks
form from the cooling and solidification of liquid rocks
Naturally occurring
formed by nature and is not man made.. ex. concrete, glass- not minerals
Sedimentary rocks
formed by the harding and cementing of layers of sediments
Intrusive
formed underground deep magma cools slowly large mineral grains coarse-grained
Igneous rock
formed when magma or lava cools minerals from distinct, interlocking grains
Extrusive
forms at or near the earth's surface lava cools quickly- little time for mineral grains to form fine grained or "glassy texture" (<1 mm)
Taste
halite has a salty taste
Moh's Hardness scale
hardness of any common mineral sale goes 1-10... 1(softest - talc)- 10(hardest - diamond)
Crystal structure
hardness, cleavage, crystal form
Magma
hot molten rock between the earth's surface
3 types of rock
igneous, metamorphic and sedimentary
Inorganic
it has not been made by or composed of life forms.. ex. fossil fuels, and pearls-not minerals
Crystalline
its atom have a specific arrangement (crystal structure)
Regional metamorphism
large areas of rock are exposed to intense heat and pressure occurs during mountain building, folding, and faulting
Scoria
like pumice is full of holes made up of denser materials- will not float
Chemical Sedimentary rocks
liquid water contains dissolved minerals as the water evaporates and the minerals precipitate and forms a mass of mineral crystals ex. rock salt and gypsum
Mafic magma
low silica content (Fe, Ca, Mg, rich) magma is hotter,thinner, and more fluid forms dark colored minerals(hornblende, Na)
Lava
magma that reaches the earth's surface
Silicates
minerals that contain oxygen and silicon - make up 90% of minerals in earth's crust
Clastic Sedimentary rocks
most sedimentary rocks
5 parts to definition of mineral
naturally occurring, inorganic, crystalline, solid, definite chemical composition
Contact metamorphism
occurs when hot magma forces its way into surrounding rock the heat of the magma bakes the rocks that are in contact with it the area is much less the the regional metamorphism the changes in the rock are less dramatic and foliation usually doesn't occur
Sediments
particles or material formed by the weathering and erosion of rocks or organic material
Crystal structure
pattern or arrangement of atoms that characterize each mineral- aka Atomic structures
Metamorphic rock characteristics
polyminerallic compsition- many minerals interconnected minerals layering (foliation), slaty, schistose,(banding) distorted or wavy rock structures stretched pebbles high percentage of mica minerals
Metamorphic Rock
preexisting rocks are changed by heat and pressure
Effects of metamorphism on rocks
pressure squeezes the grain closer together making the rock more dense and less pours heat and chemicals rearrange the particles minerals may recrystallize- new minerals may form pressure may cause distorted structure (the curving and folding of the foliation within the rock)
tetrahedron
pyramid composed of 4 equilateral triangles (SiO4 = central silicon atom surrounded by 4 atoms) - combine in a number of different ways producing many different types of minerals
Sedimentary rocks
rocks that form from an accumulation of sediments and/ or organic material
Metamorphic rocks
rocks the form from changes previously existing rocks due to heat and pressure
Streak is determined by...
rubbing of mineral on a streak plate
Ex of Clastic rocks
shale, sandstone, conglomerate
clast
solid sediments weathering from other rocks
Crystal Shape
the outward shape of a mineral specimen- Crystal Form- reflects the internal atomic structure
Hardness
the resistance of a mineral to being scratched usually determined by using the Moh's Hardness scale
Definite chemical composition
the type and ratio of elements that make up the mineral remains constant ex. NaCi- rock salt- one sodium atom for each chlorine atom
Fracture
the way in which a mineral breaks producing an uneven breaking service
properties of chemical composition: Luster
the way the mineral looks when in reflected light (metallic - shines like metal; non-mettalic 0 doesn't shine)
Florescence
these mineral will glow while under ultraviolet light
Radioactive
these minerals give off subatomic particle that will activate a Geiger counter
Double refraction
this causes two images to be seen when a object is viewed through the mineral specimen
The rock cycle
used to show how the rock types are related show the process that produces each rock type any rock type can be changed into any other rock type
Obsidian
volcanic glass (granite family) usually dark color conchoidal (shell-like) fracture
Cleavage
when a mineral with cleavage breaks, smooth or semi-smooth parallel surfaces are produced
Clast can be transported by....
wind, wave,s, running water, and glaciers