Rocks Flashcards
Neptunism
early concept presumed that rocks were originally deposited in a series of layers as a result of either chemical precipitation or deposition of material carried in suspension in the ocean
Plutonism
early thought that presumed that some rocks were formed directly by molten material that cooled and solidified on or below Earth’s surface
What are rocks made of?
minerals
What are minerals made of?
elements arranged in characteristic atomic structures
How are minerals categorized?
By the chemical elements they contain
What are the most common elements in Continental Crust?
oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium
What is an atom?
the smallest particle that retains the characteristics of an element
What is the atomic number?
the number of protons and electrons in an element
What are two types of bonds?
Ionic and covalent
What is ionic bonding
Forms due to the attraction between opposite charges; when one donates an electron to another
What is covalent bonding?
When atoms share electrons to achieve a stable structure
What are silicates?
silicon and oxygen; they form a pyramidlike structure known as the silica tetrahedron; minerals that contain both silicon and oxygen
What are minerals?
naturally occurring inorganic solids of one or more elements that have a definite chemical composition with an orderly arrangement of atoms
How are minerals characterized?
crystal form, cleavage, hardness, and color
What is crystal form?
the shape of a crystal that a mineral forms when it is free to grow unimpeded
What is cleavage?
the propensity of a mineral to break alone one or more planes
What is hardness?
the resistance of a mineral to scratching
-Moh’s scale (1-10, diamond = 10 and can scratch anything below it)
Color? Dark vs Light
Dark colored rocks= green, dark green, black, dark brown
Light colored rocks= white, pink, gray, transluscent
Other properties used in identifying rocks?
Luster-how light is reflected from a mineral
Streak-the mark formed when a mineral is scratched across an unglazed piece of porcelain
How do igneous rocks form?
These rocks form from the cooling of melted rock (magma). They can be classified as volcanic or plutonic.