Atoms, Elements, and Minerals Physical Geology 11/e, Chapter 2. Steve Kadel, Glendale Community College. Minerals. A mineral is a ……. Consistent and recognizable physical and chemical properties. Atoms and Elements. An element … An atom … Composed of 3 types of subatomic particles
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Steve Kadel, Glendale Community College
A mineralis a …….
Consistent and recognizable physicaland chemical properties
An element …
An atom …
Composed of 3 types of subatomic particles
The combining and conecting of atoms creates a compound
Protons and neutrons form the nucleusof an atom
Electrons orbit the nucleus in discrete shells or energy levels
Elements will typically be reactive unless their valence shell is full.
Positive and negative ions are attracted to one another by….
shells, so they need one more.
They can share their bonds to make them stronger. Thus covalent bonding.
Sodium has an extra electron in outer shell so it gives up to Chlorine. Clorine needs one due to only having seven so it takes Na electron into outer shell. Ionic bonding
Ionic bonding of NaCl (sodium chloride)
Everytime we add a proton, electron, or neutron, we change the atom, and if we change the atom, we change the element.
The far right column has eight electron to fill outer shell
thus they are “inert”.
Atoms of an element with different numbers of neutrons are called isotopes
Isotopes may be either stable or unstable
Stable isotopes can be used to track climate change over time
The structure of a mineral can be changed as in a diamond or graphite. Both are made of pure carbon, one is in sheets(graphite) and other is in a three dimensional structure(diamond). Chemically the same, but structurally they’re different minerals.
The color of a mineral is one of its most obvious attributes, and is one of the properties that is always given in any description. Color results from a mineral’s chemical composition, impurities that may be present, and flaws or damage in the internal structure. Unfortunately, even though color is the easiest physical property to determine, it is not the most useful in helping to characterize a particular mineral.
The color of a mineral when it is powdered is called the streak of the mineral. Crushing and powdering a mineral eliminates some of the effects of impurities and structural problems, and is a better diagnostic for some minerals than their color. Streak can be determined for any mineral by crushing it with a hammer, but it is more commonly (and less destructively) obtained by rubbing the mineral across the surface of a hard, unglazed porcelain material called a streak plate.
The luster of a mineral is the way its surface reflects light. Most terms used to describe luster are self-explanatory: metallic, earthy, waxy, greasy, vitreous (glassy), adamantine (or brilliant, as in a faceted diamond). It will be necessary, at least at first, only to distinguish between minerals with a metallic luster and those with one of the non-metallic lusters.
In some minerals, bonds between layers of atoms aligned in certain directions are weaker than bonds between different layers. Breakage will occur along smooth, flat surfaces parallel to zones of weakness. In some minerals, a single direction of weakness exists, but in others, two, three, four, or as many as six may be present.
The Mohs Hardness Scale is a relative scale. This means that a mineral will scratch any substance lower on the scale and will be scratched by any substance with a higher number. Diamond is not 10 times harder than talc or 1.1 times harder than corundum, as would be the case with an absolute hardness scale. Most often we are able only to narrow down hardness to within a certain range; for example, if an unknown mineral scratches a copper penny but does not scratch a glass plate, its hardness must be greater than 3.0 and less than 5.5. Usually this range of values is sufficient to identify an unknown.
When minerals form in environments where they can grow without interference from neighboring grains, they commonly develop into regular geometric shapes, or crystals, bounded by smooth crystal faces. The crystal form for a given mineral is governed by the mineral\'s internal structure, and may be distinctive enough to help identify the mineral. For example, quartz forms elongated, six-sided prisms capped with pyramid-like faces; galena and halite occur as cubes; and garnets develop 12- or 24-sided equidimensional forms. Interference from other mineral grains during growth may prevent formation of well-formed crystals. The result is shapeless masses or specimens that developed only a few smooth crystal faces. This type of specimen is much more common than well-formed crystals.
The specific gravity of a substance is a comparison of its density to that of water. To compare the specific gravity of any two minerals, simply hold a sample of one in your hand and "heft it," i.e., get a feeling for its weight. Then heft a sample of the other that is approximately the same size. If there is a great difference in specific gravity, you will detect it easily.
Magnetism - A few minerals are attracted to a magnet or are themselves capable of acting as magnets (the most common magnetic mineral is magnetite).
Igneous Rocks, Intrusive Activity, and the Origin of Igneous RocksPhysical Geology 11/e, Chapter 3
Steve Kadel, Glendale Community College
An aggregate of one or more minerals
Rock that is weathered and not transported is called soil
above a subduction zone
to form igneous rock
gets weathered into sediment
buried and hardened into sedimentary rock
Notice the grain size of intrusive and extrusive
Fine-grained igneous rock
Coarse-grained igneous rock
Pegmatitic igneous rock
Porphyritic igneous rock
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Bowen’s Reaction Series
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Insert new Fig. 3.23 here