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WorksheetsMinerals and Textural Differences in Rocks
Total questions: 66
Worksheet time: 1hrs 15mins
(a) are the basic building blocks from which rocks are made.
Minerals are ____ chemical compounds with ____ atomic arrangements.
(a)
Common rock-forming minerals are chemical compounds of fairly common elements such as:
silicon and aluminium
potassium, oxygen and carbon
calcium and sodium
iron and magnesium
Quartz minerals contain:
silicon and oxygen
magnesium and oxygen
iron and magnesium
sodium and calcium
Feldspar minerals contain:
potassium
magnesium and iron
sodium and calcium
aluminium, silicon, and oxygen
Clay minerals contain:
silicon
aluminium
water
oxygen
Mica minerals contain:
iron or magnesium
oxygen
aluminium and silicon
sodium
Amphibole minerals contain:
iron, magnesium calcium
Sodium, aluminium and calcium
or magnesium and oxygen
or sodium, aluminium, silicon and oxygen
Minerals of igneous rocks depend on
what chemical elements were available
the temperature and the pressure
the size of the melt
(a) refers to the physical appearance or character of a rock, such as grain size, shape, arrangement, and pattern of minerals or fragments within a rock.
Texture of igneous rocks (1 of 3):
Crystals are inter-grown
Range of crystal sizes
Low density
Does not form layers
Texture of igneous rocks (2 of 3):
May exhibit air holes (vesicles)
May be glass-like
Often have a speckled appearance
Often in bands
Texture of igneous rocks (3 of 3):
Relatively dense, meaning they are heavy
Often crystalline
Generally very hard and break with sharp edges
Made from fragments of other rocks
(Igneous) Granite is an igneous rock that has cooled very (a) . We know this because the mineral crystals in granite are quite large.
(Igneous) Basalt cooled (a) quickly than granite. We know this because the minerals are not visible to the naked eye.
The quicker an igneous rock cools, the (a) the crystals are.
(Igneous) Obsidian is a volcanic glass, which cools very (a) . Obsidian cools faster than granite or basalt. The chemical composition is silicon dioxide (the same as quartz and glass)
Textures of sedimentary rocks (1 of 3):
Made from fragments of other rocks
May exhibit air holes (vesicles)
Generally not crystalline unless formed from solution
Does not form layers
Textures of sedimentary rocks (2 of 3):
Rounded-appearing mineral and rock particles that are cemented together
Crystals / minerals often line up
Often in layers
Generally very hard, and breaks with sharp edges
Textures of sedimentary rocks (3 of 3):
Often have a speckled appearance
Often relatively soft, and may crumble or feel chalky
Low density, meaning they are light
Often crystalline
Sedimentary rocks are soft and more breathable than igneous or metamorphic rocks, and are usually less dense. Sedimentary rocks form under (a) temperature and pressure, which allows the grains to be compacted and cemented together in the process of lithification, but does not cause any significant alteration to the composition or crystals.
(Sedimentary) Conglomerate is composed of fairly large and well-rounded rock ____ and minerals. In between the ____ there may be fine-grained sediments that were caught between the larger sediments when the rock formed. This is called the matrix. Conglomerate is held together by cements that form between the grains, and vary lots from sample to sample.
(a)
(Sedimentary) Sandstone was once sand that has been (a) together. Depending on the specimen, individual sand grains may be visible. Sandstone can be made of a mix of rock, crystals, and fossils, and thus has a wide variety of colours.
(Sedimentary) Shale is composed of very ____ particles of mud, which have been compacted and cemented together. Individual mud grains are very ____, rarely visible. Shales also vary in colour.
(a)
Textures of metamorphic rocks (1 of 3):
Often crystalline
Often relatively soft, and may crumble or feel chalky
Crystals tend to regrow, recrystalise, and re-orient
May be glass-like
Textures of metamorphic rocks (2 of 3)
Made from fragments of other rocks
Lineation / foliations formed perpendicular to the direction of forces
Low density, meaning they are light
Crystals / minerals are often lined up (lineation or foliation)
Textures of metamorphic rocks (3 of 3):
Often in bands, like gneiss, or sheet-like, like slate
Often have a speckled appearance
May exhibit air-holes (vesicles)
Often relatively soft, and may crumble or feel chalky
Metamorphic rocks tend to be (a) , but have varied characteristics. A range of temperature and pressure conditions can cause metamorphism.
(Metamorphic) Schist is composed of visible minerals, mostly ____. Schists form under moderately high pressure conditions, which causes the naturally platy ____ crystals to line up, giving the rock a platy look. The ____ shows the characteristic 'squished' look of the metamorphic rocks. This is called foliated texture.
(a)
(Metamorphic) Marble is composed of exclusively large, commonly visible crystals of ____. The grey or white bands in some samples are due to impurities within the ____. Marble comes in a variety of colours, and like all rocks that have ____ in them, fizzes if you put a weak acid on it. Marble forms when any rock containing ____ is put under high temperature and/or pressure conditions.
(a)
(Metamorphic) Gneiss is composed of visible minerals that have a ____red look. Usually formed under high pressure, where the minerals separate into ____s. Gneiss formed under higher temperatures and pressures than most other metamorphic rocks, as such its' crystals have joined together and become larger.
(a)
(Metamorphic) Slate used to be a mudstone or shale before it was put under high pressure or temperatures. Slate is (a) than mudstone or shale and has a characteristic 'ting' sound when it hits a hard surface. Mudstone and slate make a 'thud' sort of sound.
What is cleavage?
No smooth planes or surfaces
The property of the mineral that allows it to break along specific internal plains to retain a smooth plain or crystal shape.
The flat surface that reflects light.
Crystal breakage along uneven or curved surfaces
What is fracture?
The flat surface of the rock that reflects light
The property of the mineral that breaks in more or less a random pattern
Crystal breakage along uneven curves or surfaces caused by an external applied force
The property of the mineral that allows it to break smoothly along specific internal plains
(Mineral Habit) Parallel masses of acicular crystals, which are normally reserved for brittle material.
Fibrous
Pisolitic
Lammelar
Spheroidal
(Mineral Habit) Acicular crystalline aggregates radiating from a central core.
Massive
Earthy
Spheroidal
Pisolitic
(Mineral Habit) The mineral is in the form of small, even grains.
Lammelar
Massive
Fibrous
Granular
(Mineral Habit) The mineral is a solid massive devoid of crystalline grain or structural properties.
Fibrous
Earthy
Massive
Spheroidal
(Mineral Habit) Massive, but properties are soft and earthy as well.
Fibrous
Earthy
Massive
Pisolitic
(Mineral Habit) Many flat sheets
Lammelar
Massive
Fibrous
Granular
(Mineral Habit) Pea-gravel like, begun at a core and formed outwards.
Spheroidal
Earthy
Pisolitic
Granular
A form of matter that has a constant composition (same proportion of elements) and consistent properties
(a)
A collection of matter in which there are multiple substances. The proportions of substances can vary.
i.e. air is a mixture of gases, rocks are mixtures of minerals
(a)
The specific elements and their proportions within a pure substance.
(a)
A 3D open-ended structure composed of one or more repeating units that describe a structure within a crystalline solid.
(a)
A characteristic that can be observed or measure without any change in chemical identity and no formation of a new product.
(a)
A (a) is a naturally occurring pure substance with a specific chemical structure.
A (a) is a mixture of minerals
(Mineral properties) Explain colour, and how to identify it.
(Mineral properties) Explain streak, and how to identify it.
(Mineral properties) Explain lustre, and how to identify it.
(Mineral properties) Explain transparency, and how to identify it.
(Mineral properties) Explain cleavage, and how to identify it.
(Mineral properties) Explain fracture, and how to identify it.
(Mineral properties) Explain hardness, and how to identify it.
(Mineral properties) Explain magnetism, and how to identify it.
(Mineral properties) Explain density / specific gravity, and how to identify it.
(Mineral properties) Observed colour of a mineral. Identified by sight.
(a)
(Mineral properties) A mineral's colour when powdered. Identified by scraping the mineral on an unglazed side of a tile.
(a)
(Mineral property) How shiny a mineral's surface is. Can be metallic, non-metallic. Identified by being held up to the light. It can be adamantine, resinous, silky, fibrous, pearly, greasy, waxy, earthy.
(a)
(Mineral property) How see-through a rock is. Identified by holding it up to the light. Can be transparent, translucent, opaque.
(a)
(Mineral property) How the mineral naturally breaks or splits to form planes. Identified by a freshly broken surface in which this structure would be seen.
(a)
(Mineral property) When the mineral is randomly broken with no structure. Identified by examining newly broken surface.
(a)
(Mineral property) How attracted it is to a magnet. Identified by touching the mineral to a magnet.
(a)
(Mineral property) A mineral's density relative to water. Identified by how heavy it is compared to an equal volume of water.
(a)
How is crystal size effected in the texture of igneous rocks?
The slower the magma or lava cools, the larger the crystals that are formed grow.
They grow bigger with slower cooling because the atoms in the melt have more time to migrate through the melt and attach to existing crystals, making them larger if the cooling process is slower.
When cooling is rapid, atoms link up with their neighbours and form small crystals.
If a melt cools very quickly, no crystal will form and the melt will solidify as glass (which has no crystal structure).
