ROCKS Flashcards
(midterm coverage)
Are the solid constituents of the earth’s crust either firm, earthy & granular. They are aggregates of one or more minerals.
ROCKS
is the science that deals with the study with the mode of occurrence, composition, classification and origin of rocks and their relations to geological processes & history.
Petrology
deals with the origin of rocks.
Petrogenesis
Origin of Rocks (6)
- Cooling of magma (molten rock) which issues from considerable depths below the earth surface.
- Precipitation of inorganic materials from water.
- Deposition of shells of various organisms.
- Condensation of a gas containing mineral particles
- Disintegration of other rocks and subsequent recombination of the resulting minerals to form new rock types.
- Action of intense heat and/ or pressure on pre-existing rock types.
Three Classifications of Rocks
- Igneous rocks
- Sedimentary rocks
- Metamorphic rocks
are formed from a once-hot, molten mass known as a magma or lava which cooled & crystallized into rock made up of aggregates of interlocking silicate minerals
Igneous Rocks
Igneous rocks occur in two general forms based on deposition:
- Extrusive Igneous Rock (volcanic rocks)
- Intrusive Igneous Rock (plutonic rocks)
Volcanic rocks are usually ____________, whereas plutonic rocks are ______________.
fine grained;
medium or coarse grained
are also called volcanic rocks that are formed at the earth’s surface as a result of volcanic activity. This activity is associated with mountain-building forces within the earth. If the rocks fracture as a result of the mountain – building forces, for example- the pressure may be released, and a sizable volume of rock will melt. The resulting magma will be forced through the fractures to the surface, forming a volcano.
Extrusive Igneous Rocks
are also called plutonic rocks, crystallized from magma that cool or hardens within the earth. The magma cools slowly resulting to the formation of coarse-grained igneous rocks.
Intrusive Igneous Rocks
In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called _______
felsic
In a widely accepted silica-content classification scheme, rocks with between 55 and 65 percent silica are ____________
intermediate
In a widely accepted silica-content classification scheme, rocks with between 45 and 55 percent silica are ____________
mafic
In a widely accepted silica-content classification scheme, rocks with less than 45 percent are __________.
ultramafic
are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth’s surface, followed by cementation.
Sedimentary rocks
is the collective name for processes that cause these particles to settle in place.
Sedimentation
Types of Sedimentary Rocks
- Clastic sedimentary rocks
- Organic sedimentary rocks
- chemical sedimentary rocks
- bioclastic sedimentary rocks
are composed of fragments of weathered rocks, called clasts, that have been transported, deposited, and cemented together. These rocks make up more than 85 percent of all of this rock type. This category includes sandstone, siltstone, and shale.
Clastic sedimentary rocks
consist of the remains of plants or animals. Coal is an ____________ made up of decomposed and compacted plant remains.
Organic sedimentary rocks
They form by direct precipitation of minerals from solution. Rock salt, for example, forms when salt precipitates from evaporating seawater or saline lake water.
Chemical sedimentary rocks
Most limestone is composed of broken shell fragments. The fragments are clastic, but they form from organic material. As a result, limestone formed in this way is called a ______________.
Bioclastic sedimentary rocks.
refers to processes that convert loose sediment to hard rock.
Two of the most important processes are compaction and cementation.
Lithification
As more sediment accumulates, its weight compacts the buried sediment , decreasing pore space and forcing out some of the water. This process is called ________.
compaction
Water normally circulates through the pore space in buried and compacted sediment. This water commonly contains dissolved calcium carbonate, silica, and iron, which precipitate in the pore spaces and ________ the clastic grains together to form a hard rock.
cement (cementation)
Sedimentary Structures
- Bedding or stratification
- Cross bedding
- Ripple marks
- Mud cracks
- Fossils
layering that develops as sediment is deposited.
Bedding or stratification -
small beds lying at an angle to the main sedimentary layering.
Cross bedding -
small, nearly parallel sand ridges and troughs that are also formed by moving water or wind.
Ripple marks -
polygonal cracks that form when mud shrinks as it dries. They indicate that the mud accumulated in shallow water that periodically dried up.
Mud cracks -
any remains or traces of a plant or animal preserved in rock – any evidence of past life.
Fossils –
(from the Greek words for “changing form” ) is the process by which rising temperature— and changes in other environmental conditions—transforms rocks and minerals.
Metamorphism
________ and ____________are the agents of metamorphism which impart energy to the rocks, sufficient to mobilize the constitutents of minerals and reassemble them. Such processes transform or metamorphose the rocks.
Heat and pressure
expresses the intensity of metamorphism that affected a rock. Because temperature is the most important factor in metamorphism, metamorphic grade closely reflects the highest temperature attained during metamorphism.
Metamorphic grade
the rate at which temperature changes. The metamorphic grade of many rocks is related to the depth to which they are buried.
Geothermal gradient –
where rise of temperature is the dominant factor. Thermal effects are brought about in contact zones adjacent to igneous intrusions, or when sediments are down-folded into hotter regions in the crust.
Thermal or Contact Metamorphism
Classes of Metamorphism (6)
- Thermal or Contact Metamorphism
- Dynamic or Dislocation Metamorphism
- Regional Metamorphism
- Hydrothermal Metamorphism (metasomatism)
- Magmatic water
- Burial Metamorphism
where the dominant control is stress, as in belts of shearing.
Example: mylonite.
Dynamic or Dislocation Metamorphism,
where both temperature and pressure have operated over a large (regional) area.
Examples: slate, phyllite, schist
Regional Metamorphism,
also called metasomatism, occurs when hot water and ions dissolved in the hot water react with a rock to **change its chemical composition and minerals. **
Hydrothermal Metamorphism,
____________ given off by a cooling magma.
Magmatic water –
________ released from rocks during metamorphism. Circulating groundwater is the main contributor to hydrothermal alteration.
Metamorphic water –
results from deep burial of rocks in a sedimentary basin.
Younger sediment may bury the oldest layers to a depth of more than 10 kilometers.
Burial Metamorphism,
- Metamorphic rock from limestone and dolostone.
- Commercially, the term is applied to any crystalline rock composed predominantly of calcite, dolomite, or serpentine and takes a good polish.
- Used predominantly in buildings and monuments, interior decoration, statuary, table tops, and novelties. Color and appearance are their most important qualities.
MARBLE
- Igneous rock.
- The many uses are due to their properties of abrasiveness, inertness and lightness.
- Utilized as lightweight aggregates, additives for pozzolan cement, abrasives, soil conditioners, carriers for insecticides, filters, extenders and insulation materials.
Pumice and Pumicite
- **Sedimentary rock. **
- The main component is calcium carbonate (CaCO3), which is widely used. In addition to widely used in chemical industry, power plant desulfurization and paper industry, the most common application of this is used as raw material for cement and steel industry.
Limestone
- Sedimentary materials.
- With the growth of infrastructure programs like the construction of circumferential highways, roads, buildings and other related projects, sand and gravel, the basic raw materials for construction, are greatly in demand.
-
Infrastructure and construction projects are the largest consumers of ________
*
Sand and Gravel
- Igneous rocks which are used in the manufacture of rock aggregates.
- rock materials which meet certain requirements as to strength, soundness, and other specifications are utilized in much the same way as sand and gravel.
Andesite and Basalt
- Igneous rock.
- locally known as adobe as a dimension stone, dates back to the Spanish era when it was utilized in the construction of churches, fortifications and houses. It was in the second half of this century that adobe made its mark as a decorative material in local architecture.
- Because of its varied texture and the ease with which it can be formed into various shapes and finish, it is now widely used to improve the appearance of houses.
Volcanic Tuff (Adobe)
- Mineral group (chrysotile, amosite, crocidolite, anthophyllite, tremolite, actinolite).
- it though considered a significant industrial mineral utilized in fireproofing, insulation, brake linings and ________ cement early in 1980’s is now considered non-commercial due to its carcinogenic property.
Asbestos
- Sedimentary material.
- it is an earthy substance consisting chiefly of hydrous aluminum silicates with colloidal material and specks of rock fragments, which generally become plastic when wet and stone-like when fired. Records of ancient brick buildings, monuments and pottery making showed that it is one of the most widespread and earliest mineral substances utilized by person.
- During Spanish times when there were no available natural building stone like limestone or volcanic tuff (adobe), the Spanish priests made bricks and tiles out of ordinary clays to build churches.
clay
- it is a hydrous calcium sulphate (CaSO4.2H2O) containing 20 percent water. It is obtained either from naturally occurring gypsum-bearing ores or from fertilizer manufacturing, as by-products.
- At present, the expanded production capacity of most cement plants in the country requires large volume of ____________ as cement retarder.
- Likewise, the manufacturing industry has greater need for ________ in the fabrication of fireproof gypsum board now proliferating among high-rise malls and condominiums.
GYPSUM
- Used as a source of magnesium metal and of magnesia (MgO), which is a constituent of refractory bricks.
- It is often used instead of limestone as an aggregate for both cement and bitumen mixes and also as a flux in blast furnaces.
- The transformation of normal limestone to dolomitic limestone or dolomite is known as dolomitization.
- Twenhofel (1950) suggested that the replacement might proceed according to the following reactions:
2CaCO3 + MgCO3 → Ca Mg (CO3)2 + Ca CO3
Dolomite/Dolostone
Mineral name – dolomite,
rock – dolostone
- in its various forms is a** very important industrial mineral and manufacturing material.** ________ occurs as SiO2 and is considered a mineral.
- As sand, it is used in the manufacture of glass containers and lamp chimneys; in the making of sheet glass, glass envelope for electric bulbs, ferrosilicon, sodium silicate, cleanser and abrasive, and as additive in the manufacture of Portland cement.
- As crushed and pulverized bull quartz, it is used in sanitary wares and flint glass containers.
*
Silica/Quartz
- is a layer-lattice mineral with the following composition, Mg3Si4O10- (OH)2.
- It is the softest common mineral with hardness of one (1) on Moh’s scale of hardness.
- The essential properties that determine the usefulness of the mineral are whiteness when ground and fired, softness and smoothness, good lubricating power, chemical inertness, a high fusion point, low electrical conductivity, and high absorption of certain types of greases and oils.
- White-firing ____ is used in the manufacture of whiteware, electrical insulators, porcelain, wall tile and other ceramic products.
Talc
- Sedimentary rock.
- A combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons.
- it is classified as a nonrenewable energy source because it takes millions of years to form. it contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.
- Apart from being a reliable energy source, coal also has a myriad of other uses, including in cement production, carbon fibers and foams, medicines, tars, synthetic petroleum-based fuels, and home and commercial heating.
Coal
- Sulfide mineral FeS2.
- The principal sources of sulfur in the Philippines are the ____ concentrate recovered as by-product from various copper mines and the natural sulfur deposits. it is used in the commercial production of sulfuric acid and sulfur dioxide.
- it is used to create iron sulfate that is used to make nutritional supplements, ink, lawn conditioner, water treatment and flocculation, moss killer, and many other chemical processes. Iron sulfate which comes from it is used to treat iron-deficiency anemia.
*
Pyrite
Industrial Minerals and Rocks (15)
- Marble
- Pumice and Pumicite
- Limestone
- Sand and gravel
- Andesite
- Basalt
- Volcanic Tuff/Adobe/Dimension Stone
- Asbestos
- Clay
- Gypsum
- Dolomite
- Silica/Quartz
- Talc
- Coal
- Pyrite (as a sulfur source)
