Minerals and Rocks
In simple terms, our planet is just a big ball of very hot stuff which, at the surface where it is exposed to space, has cooled to form crystalline solids composed of minerals. Minerals in turn are combinations of elements, which are made of smaller particles, which are made of smaller particles, which are made of..... who knows what.
To be classified as a mineral, a substance must be an inorganic, naturally formed solid, with a specific chemical formula and a fixed internal structure. For example, coal is not a mineral (it's organic), but snow meets all five (5) requirements and therefore is a mineral. Everything we know is composed of one or more of the 98 natural occurring elements. A mineral is a naturally occurring substance, representable by a chemical symbol, that is usually solid and inorganic, and has a crystal structure.
A rock is a naturally occurring solid, composed of one or more minerals or mineraloids. Rocks are natural combinations of the 5,300 minerals that exist in nature. Rocks are formed through three different processes that allows them to be classified in to three distinct types. All three types of rocks can be made up from the majority of the natural occurring minerals. These three classifications of rocks are:
1: Igneous
2: Metamorphic
3: Sedimentary
Igneous rocks are born in fire. They are formed in the wild smoldering cauldron deep within the earth where minerals are melted to a liquid state called magma. Magma which is less dense that surrounding solid rock tend to rise forcing its way to the surface. As this magma rises it cools and solidifies, producing a crystalline mixture of minerals. If magma is unable to reach the surface before it cools it forms a pluton. A pluton is formed miles under ground and forms larger crystals When a plutonic rock intrude through surrounding rock it is referred to as an intrusive igneous rock. When Igneous rock makes its way to the surface before it cools it is a volcanic rock.
Metamorphic rock, a term derived from the Greek word "meta", meaning change, and "morphe" meaning form,is another classification of rock. Most metamorphic rocks are the oldest formed during major mountain forming events when heat caused from the friction, and pressure caused from one plate of the earths crust sliding beneath another plate changes igneous rock. Igneous rock's form is changed. Certain metamorphic rock is form from extreme pressure only.
Over time all rocks break down into smaller particles or decomposes. Often the individual mineral concentrate together and over time resolidify. An example is quartz an igneous form of silica decomposes in to sand, the sand solidifies into sandstone and over time the sandstone forms quartzite which is the metamorphic form of quartz.
The majority of rocks spent time deep in the inferno miles below the surface of the earth. Some rocketed upward while other rocks oozed up through cracks in the crust and then pushed to the surface. Wind, rain, waves, and ice helped shape the rocks. Each rock and landform carries its own story within its composition and structure.
Common rock forming minerals are:
Feldspar
Quartz
Mica
Hornblende
Augite
Olivine
Calcite
magmatic differentiation—processes by which chemically different igneous rocks, such as basalt and granite, can form from the same initial magma. High-temperature minerals can crystallize and settle out, causing the molten material to be concentrated with component that may later form rock enriched in low temperature minerals (such as granite). The last rocks to crystallize in a magmatic intrusion will be enriched in low temperature minerals (quartz, mica, and potassium- and sodium- feldspars).
To be classified as a mineral, a substance must be an inorganic, naturally formed solid, with a specific chemical formula and a fixed internal structure. For example, coal is not a mineral (it's organic), but snow meets all five (5) requirements and therefore is a mineral. Everything we know is composed of one or more of the 98 natural occurring elements. A mineral is a naturally occurring substance, representable by a chemical symbol, that is usually solid and inorganic, and has a crystal structure.
A rock is a naturally occurring solid, composed of one or more minerals or mineraloids. Rocks are natural combinations of the 5,300 minerals that exist in nature. Rocks are formed through three different processes that allows them to be classified in to three distinct types. All three types of rocks can be made up from the majority of the natural occurring minerals. These three classifications of rocks are:
1: Igneous
2: Metamorphic
3: Sedimentary
Igneous rocks are born in fire. They are formed in the wild smoldering cauldron deep within the earth where minerals are melted to a liquid state called magma. Magma which is less dense that surrounding solid rock tend to rise forcing its way to the surface. As this magma rises it cools and solidifies, producing a crystalline mixture of minerals. If magma is unable to reach the surface before it cools it forms a pluton. A pluton is formed miles under ground and forms larger crystals When a plutonic rock intrude through surrounding rock it is referred to as an intrusive igneous rock. When Igneous rock makes its way to the surface before it cools it is a volcanic rock.
Metamorphic rock, a term derived from the Greek word "meta", meaning change, and "morphe" meaning form,is another classification of rock. Most metamorphic rocks are the oldest formed during major mountain forming events when heat caused from the friction, and pressure caused from one plate of the earths crust sliding beneath another plate changes igneous rock. Igneous rock's form is changed. Certain metamorphic rock is form from extreme pressure only.
Over time all rocks break down into smaller particles or decomposes. Often the individual mineral concentrate together and over time resolidify. An example is quartz an igneous form of silica decomposes in to sand, the sand solidifies into sandstone and over time the sandstone forms quartzite which is the metamorphic form of quartz.
The majority of rocks spent time deep in the inferno miles below the surface of the earth. Some rocketed upward while other rocks oozed up through cracks in the crust and then pushed to the surface. Wind, rain, waves, and ice helped shape the rocks. Each rock and landform carries its own story within its composition and structure.
Common rock forming minerals are:
Feldspar
Quartz
Mica
Hornblende
Augite
Olivine
Calcite
magmatic differentiation—processes by which chemically different igneous rocks, such as basalt and granite, can form from the same initial magma. High-temperature minerals can crystallize and settle out, causing the molten material to be concentrated with component that may later form rock enriched in low temperature minerals (such as granite). The last rocks to crystallize in a magmatic intrusion will be enriched in low temperature minerals (quartz, mica, and potassium- and sodium- feldspars).
Scott has a lot of photos on his website: http://www.burnworthphotography.com/
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Actually it does not matter what a rock is made from, if you like a rock that you find take it and enjoy it's beauty.
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Personally I enjoy researching the rocks I find trying to figure out what minerals they contain, why and how they were formed.
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A new find.
A well water worn crystal, a couple of the faces are apparent. The current surface is frosty - due to the abrasion from the tumbling through miles of the river. Natural rock tumbler, but poor choices of grit. 
I'm not positive on just what variety of rock this specimen is.
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Harder than Quartz +7 on mohs scale
Specific Gravity - 3.6 |
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Minerals are identified by their characteristics. Such as:
Hardness Color Streak Luster Diapheny Cleavage Fracture Crystal System Hardness: measured in what is called Mohs scale, a scale that reflects a minerals scratch resistance. The scale goes from 1 to 10, 10 being diamond and the hardest. A higher number can scratch all numbers below it. Mohs Scale 1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite 6 Feldspar 7. Quartz 8. Topaz 9 Corundum 10 Diamond |
Quartz
Hardness - 7 Color - clear to red Streak - white Luster - vitreous Diapheny - Transparent Cleavage - rhombohedral Fracture - conchoidal Crystal System - Hexagonal |
Quartz is the name given to a broad range of rocks that contain a high percentage of Silica (Si) and Oxygen (O). The most abundant mineral is feldspars the second most abundant mineral is quartz.
Pure quartz is 7 on Mohs Scale of hardness.
Pure quartz has a specific gravity of 2.65.
More information on Quartz can be found at: www.quartzpage.de
Pure quartz is 7 on Mohs Scale of hardness.
Pure quartz has a specific gravity of 2.65.
More information on Quartz can be found at: www.quartzpage.de
Crystal quartz cabochon with some inclusions of iron
Macrocrystalline Group 
Agate
Cryptocrystalline Group |
Purplish Quartzite
Quartzite is a metamorphic form of quartz. Notice the individual small 'grains' of SiO2 in this example. 
Jasper
Cryptocrystalline Group |
Major varieties of Quartz
- Chalcedony - white or lightly colored
- Agate - Multi-colored, semi-translucent to translucent
- Onyx - Agate where the bands are straight, parallel and consistent in size
- Jasper - Opaque - typically red to brown
- Aventurine - Translucent with small inclusions (usually mica) that shimmer
- Tiger's eye - Fibrous gold to red-brown exhibiting chatoyancy
- Rock crystal - clear colorless
- Amethyst - transparent - purple
- Citrine - Yellow to reddish orange to brown, greenish yellow
- Prasiolite - Mint green, transparent
- Rose quartz - Pink, translucent
- Rutilated quartz - contains needles of rutile (acicular inclusions)
- Milky quartz - white, translucent to opaque - bull quartz
- Carnelian - translucent reddish-orange
- Dumortierite - contains dumortierite crystals
Opal is the name for Si O2 H2O: Hydrated amorphous quartz - amorphous is a non-crystalline solid that lacks the long-range order characteristic of a crystal.For more information on opals please goto http://gemhunter.webs.com/opal.htm
Cabochons setting on matrix found on Cedar Rim, Wyoming. This shows the different varieties of opal from this location.
