1. Igneous Rocks: rock formed when magma or lava cools & hardens
Igneous comes from the Latin word ‘ignis’ which actually means fire. Igneous rocks are a word used for rocks that have formed by the cooling and hardening of molten lava or magma. The atoms and molecules of melted minerals are what make up magma.
The upper section of the Earth’s crust is made up of around 95% igneous rock
There are over 700 different kinds of igneous rocks that have been identified so far.
their minerals and global chemistry gives information about the composition of the mantle
Rocks are made up of different minerals that have different melting points. When hot rocks begin to melt deep down beneath the surface, some of the minerals start to melt but others stay solid.
The rock of the Earth’s mantle layer only begins to melt in a few zones where it is disturbed in some way
Rocks melt because of the heat beneath the Earth’s surface, as well as other factors such as changes in pressure, or the presence of water within the rock.
Magma reaches the surface because of pressure squeezes the rock like a sponge, forcing the melted material (magma) to rise toward the surface.

2. Igneous Rocks Extrusive Rock: Formed from lava that erupts from
volcanoes then cools
and hardens on Earth’s surface
Magma also varies in temperature, and in how much dissolved gas it contains.  All of these factors control the viscosity of the magma (whether it is relatively runny or very thick and sticky).
Viscosity, in turn, controls how magma behaves as it rises through the crust, and erupts at the surface.
The rate at which magma cools controls the grain size of the igneous rock that is formed. More rapid cooling produces finer-grained rocks

3. Igneous Rocks Extrusive Rock: Formed from lava that erupts from
volcanoes then cools
And hardens on Earth’s surface
glassy
Igneous rocks formed on the surface cool down in just a matter of a few hours. The crystals in these rocks can be microscopically small.
Minerals are
not organized
into crystals.

4. Obsidian rocks : lava cools so quickly above ground that atoms are unable to arrange themselves into a crystalline structure. . Obsidian is actually glass and not a mixture of minerals. Obsidian goes through a process in which it turns from glass to a rock.
The edges of this rock are very sharp. Since the Stone Age, people have used obsidian to make cutting tools and tips for their arrows and spears. Obsidian is commonly used during surgical procedures because it is often sharper than traditional surgical tools.
Obsidian is used as a gemstone in jewelry.
The different colors are due to small amounts of different materials (iron, magnesium) – like putting drops of ink into a glass of water.

5. scoria
pumice
Scoria (10) forms when magma containing a bunch of gas flows from a volcano or is blown out during an eruption. As the molten rock emerges from the Earth, the pressure upon it is reduced and the gas starts to escape in the form of bubbles. If the molten lava hardens and solidifies before the gas has escaped, the bubbles become cavities, or holes in the rock. This dark-colored igneous rock with the trapped bubbles is known as scoria. The red variety of scoria (it also comes in black) is commonly used as landscaping pebbles at Taco Bell. Landscapers know this rock as lava rock.
Pumice is a froth, or foam, (pop poured too fast) of molten rock. It is rapidly blown out of a volcano, with so much air , that it forms bubbles as it quickly loses pressure and cools. There are left so many of these air holes, that when hardened and solidified, it floats on water.

6. Close examination of fresh pumice shows its glassy nature
Close examination of fresh pumice shows its glassy nature. Older, weathered pumice looses its glassy appearance

7. Igneous Rocks Extrusive Rock: Formed from lava that erupts from
volcanoes then cools
And hardens on Earth’s surface
glassy
Fine-grained
Minerals are
not organized
into crystals.
Crystals are too
small to be
seen without
a microscope

8. basalt
Basalt forms when lava cools quickly. Most of the ocean floor and the Hawaiian Islands are made of basalt. It is also found on the Moon, Venus and Mars.  Because it is a common rock and very hard, people used basalt for early choppers and for grinding stones to grind grains like millet and barley. Roman engineers paved a lot of Roman roads with basalt, and today engineers still use a lot of ground-up basalt to make asphalt to pave roads.
Rhyolite(14) is formed when lava with a very high silica content cools quicly.
rhyolite

9. The Giant’s Causeway, in Ireland, was made from a lava flow that erupted over 55 million years ago. The lava cooled, and as it did this it split and formed about 40,000 basalt pillars, which look like humongous stepping stones that reach out into the ocean

10. Igneous Rocks Intrusive Rock: Formed from magma that cools and hardens
inside the Earth
There are places on Earth that are so hot that rocks melt to form magma. Because magma is liquid and usually less dense than surrounding solid rock, it moves upward to cooler regions of the Earth. As the magma loses heat, it cools and crystallizes into an igneous rock. What does that mean – crystalize?
When a liquid cools to a solid, the substance is said to have crystallized. This means as magma cools, the elements in the magma form solid bonds with their neighbors in a repetitive pattern. The minerals form into bigger and bigger crystals until they smash into other crystals. Once enough mineral crystals smash together so hard that they can't be taken apart, the minerals have formed into an intrusive igneous rock. Igneous rocks that form deep within the Earth’s crust where temperatures are very high might take thousands of years to cool down. This causes the crystals to be much larger

11. Igneous Rocks Intrusive Rock: Formed from magma that cools and hardens
inside the Earth
Course
grained
Igneous rocks that form deep within the Earth’s crust where temperatures are very high might take thousands of years to cool down. This causes the crystals to be much larger,
Larger crystals
all roughly the
same size
pegmatite

12. granite
diorite

13. Igneous Rocks Intrusive Rock: Formed from magma that cools and hardens
inside the Earth
Porphyritic
Course
grained
Large crystals
are scattered
on a back-
ground of
small or
microscopic
crystals
some crystals started to form before others and had therefore more time and room to grow.
porphyry
Larger crystals
all roughly the
same size

14. andesite

15. Igneous Rocks Extrusive Rock: Formed from lava that erupts from
volcanoes then cools
And hardens on Earth’s surface
Intrusive Rock:
Formed from magma that
cools and hardens
inside the Earth
glassy
Fine-grained
Porphyritic
Course
grained
Large crystals
are scattered
on a back-
ground of
small or
microscopic
crystals
Minerals are
not organized
into crystals.
Crystals are too
small to be
seen without
a microscope
Larger crystals
all roughly the
same size

16. compacting and cementing
Sedimentary Rocks:
Rock formed from the
compacting and cementing
of sediment
made when sand, mud and pebbles get laid down in layers. Over time, these layers are squashed under more and more layers. Eventually, the layers are lithified – turned to rock
The sediment (the sand, mud and pebbles) that make up Sedimentary rocks come from other rocks that have been worn down by wind, rain and snow.
Sedimentary rocks cover the majority of the Earth's rocky surface but only make up a small percentage of the Earth’s crust compared to metamorphic and igneous types of rocks.
breaks down rocks into small pieces known as sediment. This sediment is carried away by wind or water. The sediment eventually lands somewhere as sand or mud. Over time, new sediment piles on top of the old. The older layers become compressed and hard. In time, the sediment turns to rock. Sedimentary rocks only form about 8 percent of the rocks on Earth that cover the other types of rocks like a thin coat of paint. Even though they are only a tiny percentage of the rocks on Earth, they are very important. They tell us a lot about the history of life on earth because sedimentary rocks are the only type of rock that can hold fossils and they are formed in layers with the oldest rocks on the bottom and the newest rocks on the top.

17. Sedimentary Rock
1. Clastic: Made of fragments of previously existing rocks
Over the course of millions of years, the igneous rocks are weathered down by forces of wind and water. Fine particles of dirt begin to cover the landscape. Often, these small rock particles end up being suspended in water, and find their way to the bottom of lakes, streams, and the ocean. Slowly, the layer of sediment on the bottom of lakes, and especially on the bottom of the ocean grows deeper and deeper, reaching depths of thousands of feet. The weight of all the sediment becomes immense, pushing down on lower layers of sediment with tremendous force. In addition, a number of minerals, which act like cement, bond the sediment together, causing it to form sedimentary rock.
Each layer is like the page of a book. One piece of paper is not heavy. But a stack of telephone books is very heavy and squishes anything underneath. Over time the layers of sand and mud at the bottom of lakes and oceans turns into rocks called sedimentary rocks. Shale is clay that has been hardened and turned into rock. It often breaks apart in large flat sections. The Earth’s crust is slowly moving. Did you know that the Atlantic Ocean is getting wider at about the rate your fingernails grow, or that India is barging its way slowly northward into the continent of Asia?
The huge forces that move continents stretch and squash parts of the Earth’s crust., generating earthquakes and building mountains. They cause rocks near the surface to be fractured and faulted.

18. Sedimentary Rock
Clastic: Made of fragments of previously existing rocks
Rounded pebbles cemented by clay, mud, and sand
So how does rock become broken down in the first place to form the sediments that make up sedimentary rocks? Over time water, wind, heat, and ice wear the rock down causing it to fall apart. This process is called weathering and erosion. The weathered bits of rock are carried by what geologists call agents. Agents are streams, rivers, wind, glaciers, or really anything else that carries the bits of weathered rock away from the large rock that formed them. The most common agent is water in the form of streams or rivers. The weathered bits of rock are carried by the agent until the agent can't move them anymore. The weathered bits of rock pile up into a big pile. The weathered rocks are called sediments. The pile is called a sediment bed. Sediments are usually classified by size: Gravel is the biggest, sand is the next smallest, followed by mud, and silt is the smallest. Clastic sedimentary rocks are sedimentary rocks formed out of broken down bits of rocks. There are several kinds of clastic sedimentary rocks; they are categorized by the size and sometimes the shape of the pieces that make up the rock.
puddingstone

19. conglomerate
Conglomerates are made from bits of rounded gravel that were deposited by the agent, usually water. Over time the wet pile of sediments becomes so heavy that the gravel gets compacted together, and minerals in the water cement the bits of gravel together. The only difference between conglomerates and breccias is: Conglomerates are made from rounded gravel and breccias (30) are make from angular gravel.
breccia

20. Sedimentary Rock
Clastic: Made of fragments of previously existing rocks
Rounded pebbles cemented by clay, mud, and sand
Small sand-sized grains
Sandstone is basically the same.

21. sandstone arkose feldspar
Piles of sand are piled up by water or wind and over time the piles get so heavy the sand is pressed together and cemented by minerals found in ground water. Sandstones are the color of the sand that composed them – red, white, brown, etc. They will often display banding resulting from successive periods of deposition. Fossils are often found in sandstone.
Arkose (25) is sandstone with at least 25% . It is commonly coarse-grained and usually either pink or gray (depending on the color of feldspar). Arkose is a type of sandstone that contains lots of feldspar grains.
arkose
feldspar

22. Sedimentary Rock
Clastic: Made of fragments of previously existing rocks
Rounded pebbles cemented by clay, mud, and sand
Small sand-sized grains
Grains smaller than sand. Composed of silt and clay-sized
mineral particles that we call “mud”
Mudstone is the same as sandstone except the particles of rock that make up the mudstone are too small to be called sand. As the name sounds, the rock used to be mud that was buried and hardened into rock.

23. shale
Siltstone is made from even smaller particles than mudstone. These types of rocks are sometimes called slate. Like “ripple marked” sandstone, mudstone can have marks made by water on it. Sometimes when mud hardens the surface cracks; these cracks can be preserved and harden into rock. Fossils can also be found in mudstone and siltstone.

24. Organic: made of organisms: directly or indirectly
from material that was once living.
Biochemical, or organic, sedimentary rock is made from the debris of life. Hmmm. What could that be?

25. Organic: made of organisms: directly or indirectly
from material that was once living.
Made of shells of sea creatures
Animals use calcium to form their shells. After the animal dies, the shell falls apart and the calcium combines with other elements and minerals and hardens into rock. Fossils are very common in this type of rock

26. limestone Calcareous Tufa
Limestone is often made from the fossilized remains of ocean life - decayed animal shells, that died millions of years ago.
Calcareeous Tufa (28) is formed near springs where calcium carbonate dissolved in the water and is deposited on plants, twigs, or other debris. - it is a light and more porous (holes, or openings) - form on limestone.
Calcareous Tufa

27. chalk
Chalk is a soft, white form of limestone

28. The White Cliffs of Dover in England are made from the shells and remains of trillions of tiny animals that died more than 65 million years ago.

29. Organic: made of organisms: directly or indirectly
from material that was once living.
Made of shells of sea creatures
Formed from the remains of plants: coal
In swampy areas, plants die but they do not decay. Instead, they turn into peat. When the peat is compressed over millions of years, it becomes coal. Around 300 million years ago the world was covered with tropical swamp forest. When these plants died they fell into the swampy earth and over time were buried. Over millions of years they were changed into coal by pressure from the layers of rock above them.

30. chemical: formed when a lake dries up, leaving large
amounts of minerals that were dissolved in the water
Most of chemical sedimentary rocks come from minerals left behind by evaporated water! Halite is the mineral name for the substance that everyone knows as "salt." Its chemical name is sodium chloride, and a rock composed primarily of halite is known as "rock salt."
Mineral rich water drips into
the cave

31. Metamorphic Rocks: rocks formed from chemical reactions,
heat, and/or pressure
Metamorphic rocks are so called because they always begin as another type of rock. The word metamorphic literally means "changed form".
Metamorphic rocks form deep within the Earth when heat and pressure are applied to either igneous rocks or sedimentary rocks – or even other metamorphic rocks.. This heat and pressure in essence cooks the rocks, changing their structure substantially.
The rocks become soft and pliable, and the chemicals within them are rearranged so that the final rock is very different than the original rock.
How do the rocks get deep inside the earth? Plate tectonics! The large plates that make up the crust of the earth are always moving. Sometimes they slam into each other. Sometimes they grind past each other. Sometimes the plates are pulling apart forming large cracks called rifts. Sometimes one plate dives under another plate. Rocks near tectonic plates may change because of the intense pressure and heat generated where two plates meet and rub against each other.
Metamorphic rocks are formed from the pressure and heat caused by the plates crashing into each other.

32. Metamorphic Rocks
When rocks are buried deep within the Earth, tremendous heat,
great pressure, and chemical reactions may cause them to change
into different rocks with different textures and structures
Intense pressure or heat may cause the stones undergo metamorphosis and harden and develop new crystals. (chemical changes)
The final state of a metamorphic rock depends on the amount of pressure the rock was subjected to, the amount of heat the rock was subjected to, and the amount of time the rock was subjected to pressure and heat.

33. layers or bands (foliated)
Metamorphic Rocks
When rocks are buried deep within the Earth, tremendous heat,
great pressure, and chemical reactions may cause them to change
into different rocks with different textures and structures
Mineral crystals are arranged
In parallel, thin, flat
layers or bands (foliated)
The first kind of metamorphism happens when rocks simply get buried by new rocks formed on top of them. The weight on top of rocks forces them deeper into the earth. The deeper the rocks are pushed into the ground the more they become exposed to heat. The heat and pressure cause the rock to change into a new rock. This type of metamorphism is is the most common form of metamorphism. However, if the heat melts the rock and then the rock cools down it is an what? igneous rock, not a metamorphic rock.

34. = slate schist gneiss or Garnet schist
Metamorphic rocks are formed from different rocks. .
Schist is formed from sedimentary rocks like mudstone or siltstone – or from slate- another type of metamorphic rock
Garnet schist (20) – schist with garnet crystals
Slate is formed from shale. As a matter of fact, slate and shale look so much like each other, the best way to tell them apart is to lightly tap them with a metal object like a coin. Slate and shale make different sounds when tapped. When tapped, slate has a slightly more metallic sound than shale. Shale makes a kind of hollow thumping sound. Many metamorphic rocks are made of layers that can be split apart. Slate is often split to make thin, durable roofing tiles.
gneiss or
Garnet schist =

35. gneiss
Gneiss is formed from ingenious rock, like granite or diorite

36. Metamorphic Rocks
When rocks are buried deep within the Earth, tremendous heat,
great pressure, and chemical reactions may cause them to change
into different rocks with different textures and structures
NOT arranged in layers and
do not break into layers
(unfoliated)
Changes in the temperature and pressure conditions cause the minerals in the rock to become unstable so they either reorient themselves into layers (foliation) or recrystallize into larger crystals, all without undergoing melting.
Erosion and uplifting the rock will bring it to the Earth’s surface. Uplift is the key to the rock cycle, as it allows us to see rocks that were once deeply buried beneath the surface.
If rocks did not get uplifted to form hills and mountains, then the processes of weathering and erosion would long ago have reduced much of the world’s land-masses to low-lying, flat plains.
Weathering and erosion, transport and deposition would all effectively stop.
Mount Everest is made of limestone that must have originally formed on an ancient sea floor because it contains fossils of marine creatures.

37. = = marble limestone talc
One very common metamorphic rock is marble. Marble is formed when heat and pressure are applied to limestone for many thousands of years.
Soapstone (19): A metamorphic rock that consists primarily of talc with varying amounts of other minerals =
talc

38. = coal anthracite quartzite
Anthracite (22) is a high grade form of coal that has been compacted and purified by metamorphism
Quartzite (17) is formed from quartz sandstones. Heat and pressure recrystallized it so that the individual grains of sand are not noticible. May come in a variety of color. Very resistant to erosion so they are among the oldest known exposed rocks.
quartzite

39. hornblende amphibolite
Amphibolite (15) is a coarse-grained metamorphic rock that has minerals such as the hornblende as its primary ingredient.