2 VocabularyRadioactivity-the spontaneous process through which unstable nuclei emit radiation.Lava-magma that flows out onto Earth’s surface.Igneous rock- rocks formed from the crystallization of magma.
3 VocabularyPartial melting- the process by which some minerals melt at low temperatures while other remain solids.Fraction crystallization- the process by which different minerals from at different temperatures.Bowen’s Reaction Series- a model that describes the relationship between cooling magma and mineral formation.
4 Composition and Origins of Magma I. Composition of magmaMagma is a mixture of molten rock, gases, and mineral crystals.The elements in magma are the eight major elements in Earth’s crust.1. The most abundant compound in magmais Silica (SiO2).C. Magmas are classifies as basaltic, andesitic, andrhyolitic.1. Their classification depends on how muchsilica they contain.
5 Composition and Origins of Magma TemperaturePressureIncrease with depthIn Earth’s crust.Increases with depth under the surfaceFactors in theformation ofmagmaThis is known as the geothermal gradient.Which increases the melting point of rockWater contentMineral contentAs this increases, the melting point decreases.Different minerals have different melting points.
6 How Rocks MeltWhen a rock begins to melt, the minerals with the lowest melting point melt first. The elements in these minerals from the liquid part of magma. As other minerals melt, the elements in those minerals are added to the magma and change its composition. The opposite happens as the magma cools. The elements in the minerals are removed from the magma in the order that the minerals crystallize, which is fractional crystallization.
8 Partial MeltingPartial melting is when different minerals within a rock melt at different rates. When different minerals are melted new elements are added to the magma mixture changing the chemical composition.
9 SynthesizeBoth branches show that minerals from in predictable patterns in cooling magma. However, in the right branch, the feldspar minerals undergo continuous change. The iron-magnesium minerals, in the left branch, undergo abrupt changes.
10 Section 5.2 VocabularyMagma- molten material found under Earth’s surface.Intrusive Rock- Igneous Rock that cool slowly beneath Earth’s surface.Extrusive Rock- Igneous rock that cool quickly on Earth’s surface.Granitic Rock- Light-colored rock high in silica and contains quartz and feldspar.Basaltic Rock- Dark-colored rock low in silica and contains iron and magnesium-rich materials.
11 Section 5.2 Vocabulary Cont. Texture- the size, shape, and distribution of crystals or grains that make up a rock.Porphyritic texture- characterized by large, well-formed crystals surrounded by finer-grained crystals of the same mineral or different minerals.Vesicular Texture- A spongy appearance caused by broken gas bubblesPegmatite- veins of extremely large grained minerals.Kimberlite- a rare, ultramafic variety of peridotite that forms pipe like structures and which sometimes contain diamonds.
12 Types of Igneous Rock Intrusive -Coarse-grained -Cool slowly -Form beneath surfaceEx. graniteExtrusive- Fine-grained- Cool quickly- Form above surface- Ex. RhyoliteIgneous RocksFormed by crystallization of magma
13 Mineral Compositionbasalt: __________________________________________________________2. obsidian: ______________________________3. peridotite: ___________________________________________________4. diorite: ________________________________________________________5. pegmatite: _________________________A fine-grained rock containingplagioclase, feldspar, biotite, pyroxene, amphibole, and olivineA felsic extrusive, noncrystalline rockA rock that contians onlypyroxene and olivineA coarse-grained rock that is mostlywhite, gray, and blacka very coarse-grained rock thatcontains potassium feldspar
14 Grain SizeDescribe the conditions that cause igneous rocks to form large grains or no visible grains.Intrusive igneous rocks are formed when magma cools slowly beneath Earth’s surface, so large crystals have time to form. Extrusive igneous rocks cool quickly because they are exposed to air and moisture on Earth’s surface, so visible crystals do not have time to form.
15 Igneous Rocks as resources List two characteristics of igneous rocks that make them good building materials.1. They have interlocking grain textures, which give them strength.2. They contain minerals that are resistant to wearing.
16 The fluid from which Magma crystallizes Contains high levels Ore DepositsThe fluid from whichMagma crystallizesContains high levelsof ______________________________.Silica, water, andLeftover elementsThe fluid fills___________________.Cracks, andVoids in therock
17 The fluid solidifies to form ____________ containingMetals such as _____,_______, ____, _______, andRare elements such as________ and __________.Quartz veinsgoldsilverleadcopperlithiumberylliumAnswer the synthesize question.
18 Other InformationIgneous is Latin for “from fire”