Welcome to my web page on minerals.
This site is a very basic view on the world of minerals. I have tried to
keep it simple so it is easy for anyone to understand but I believe when
you finish exploring this page you will have a good base to continue learning
and expand on your knowledge. This page was an assignment for an ES111 Earth
Science lab and the inspiration for the project from chapters 1, 2, 3, and 4
on rocks and minerals in Johnston, P., Aber, S.W., & Ye, H. (1996).
Introduction to earth science lab. Edina, MN: Burgess Publishing.
QUARTZ Image by
Peru Huaron (2)
A Mineral is a natural occurring inorganic solid that possesses a definite chemical structure which gives it a unique set of physical properties. Therefore, for anything on Earth to be considered a mineral, it must have the following things...
1. It must be
naturally occurring.
2. It must be
inorganic (was never alive)
3. It must be
a solid.
4. It must have
a definite chemical structure.(3)
A Rock is simply a variety of minerals put together. Minerals are the building blocks that make up rocks.
Minerals have several different ways
of being identified. There is about 4000 different kinds of minerals known
to man and of these known only 3 dozen of them make up the majority of
the Earths crust.(3) Now your probably thinking
what I thought at first, how do they keep them all in order and how do
they know the difference between them. Well I will tell you it is easier
than it sounds. When they find a mineral they put it through a series
of basic physical tests, described below, to figure out the mineral's
identity.
One test involves LUSTER. Luster is the mineral's ability to reflect light and either have a metallic finish such as pyrite or a nonmetallic look, such as the vitreous or glassy look of quartz. Another test involves the use of COLOR, which is simply the mineral's color to the naked eye. However, some minerals are display a different color in a powdered form, which sets up the next test of the STREAK. A mineral's streak is the color it appears in a powdered form. This is done by rubbing the mineral across a streak plate, unglazed porcelain, creating a powder of the mineral to see the the mineral's true color.
Probably the most useful property of a mineral is probably it's HARDNESS. Which is a measure of resistance of a mineral to abrasion or scratching. Geologists use a standard scale called the MOHS SCALE. Mohs scale consists of ten minerals arranged in hardness from 1 - 10, with 10 being the hardest and 1 being the softest. A finger nail has a hardness of 2.5, a copper penny has the hardness of 3, and a piece of ordinary glass has the hardness of 5.5. For example, the mineral calcite has the hardness of 3, which means that your fingernail cannot scratch it because it is harder 2.5 and calcite cannot scratch glass because it does not have a hardness of 5.5.
A reaction of a mineral to stress and
strain results in a fracture or cleaving of the specimen. CLEAVAGE
tests the mineral's ability to break, or cleave, along planes
of weak bonding. A mineral that has good cleavage would break off creating
a very smooth face and can have cleavage in 1, 2, 3, 4, or 6 different directions.
When a mineral does not have cleavage,it is said to FRACTURE.
Minerals with bonding strength the same in all directions fracture and
a common look is similar to the way glass breaks, or a conchoidal fracture.
The next thing we should talk about is the different mineral groups or classifications. The two most common are the SILICATES and the CARBONATES. The silicates are made up of the two most common elements on the Earth which are silicon and oxygen. They make up 3/4 of the Earth's continental crust and in turn, make up the most commonly found minerals. They are usually formed within molten rock as it cools near or on the Earth's surface. The basic surroundings of the molten rock as it cools determines what kind of mineral formed. So if molten rock crystallizes near the top of the earth's surface it would end up being a different mineral than one that crystallized deep beneath the surface due to different pressures and temperatures. The carbonates are made up of carbon and oxygen and are the second most common mineral group found. An important ingredient in the carbonates is mineral calcite. Calcite makes up two well known rocks limestone and marble. Many carbonates have commercial uses and a great economic value.
Earth has mineral resources yet unfound or
mined at this time. These resources that can be recovered are called
RESERVES. Minerals that can be found by mining are called
ORES and are extracted, not for the good of
humankind but, for profit.
Bob's Rock Shop Good Rock Pictures & Info
The Image Great Information Site
Mineral Collectors Page Good source with a lot of links
Avalon Crystals
Good alternative information source
Works Cited
(1) Buelens, Johan H. (1998).
Mineral Photography [WWW Document]
(2) Huaron, Peru (1998).
The Image [WWW Document]
(3) Tarbuck, Edward J., and Frederick
K. Lutgens (1997). Earth Science (8th ed.).
Prentice Hall:
This page was
created October 24, 1998
If you have any
questions regarding minerals or how to make your own web page feel free
to drop me an e-mail and I will try my best to answer any question you
have.
Return to the
Student's Index page
http://www.xs4all.nl/~mineral/photo/photo.html.
http://www.theimage.com/mineral/quartz/quartz.html
New Jersey. pgs. 18-30.