Week 3 term 3

 Mineral: is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition.  Naturally occurring means that nature has to make it. Things like steel, bricks, glass, plastic are not naturally occurring and can not be a mineral.  Inorganic: not formed from living things or the remains of living things.

 Solid, a mineral is always a solid.  Crystal structure, the particles of the mineral line up in a pattern that repeats over and over again.  Definite chemical composition, this means that a mineral always contains certain elements that are in a definite proportion.  Almost all minerals are compounds. Example is quarts. It = 1 part silica and 2 parts oxygen.

 Today geologist recognize about 3,800 different types of minerals. With so many it can be over- whelming to tell them apart.  Each mineral has characteristics properties that can be used to identify it. Learning theses thing can help you to identify many different common elements present around you.

 Color: the color of a mineral can easily seen but is not a good way to positively identify a mineral. There are few minerals that have a very specific color and they are the only ones to have that color.  Example: gold, pyrite, and chalcopyrite are all gold. And malachite is always green, azurite is always blue. No other minerals look quite like these.

 Streak: is the color of a minerals powder as its streaked along unglazed tile. Surprising the streak and the color are often different.  Example pyrite is always a gold color but its streak is greenish black.  Luster : is how light is reflected from the material. Minerals containing metals often are shiny, other terms used are glassy, waxy, earthy, pearly.

 Density: Each mineral has a characteristic density. Density is the mass in a given space, or mass per unit volume.  If you have two different samples that are the same size you can tell the one with more density because it will be heavier.  Example: galena is much more dense than quartz. The same size sample of galena will weigh three time as much as the quartz.

 Hardness: hardness is one of the best ways to determine a minerals identity. In 1812 an Austrian named Fredric Mohs. Came up with a scale of hardness called Mohs hardness scale.  This scale consists of 10 different minerals in increasing hardness. It ranks them from the softest to the hardest.  Hardness is determined by the scratch test. A mineral can scratch any mineral softer that its self. But can be scratched by any mineral hard than it as well.

 To determine the hardness of a mineral not on the scale, you could use minerals on the scale to find its hardness.  Example: azurite isn't ion the scale if you tried to scratch it with talc(1) or calcite(3) it wont scratch but Apatite(5) will so its hardness is about 4.

 Each mineral has a way the crystal will grow. This is done at the atomic level. Atom by atom the structure takes form. There are six different forms.  Cubic  Hexagonal  Tetragonal  Orthorhombic  Monoclinic  Triclinic

 Cleavage: a mineral that splits easily along a flat surfaces.  Example: mica  Fracture: minerals that do not split apart evenly, instead they have a characteristic type of fracture.  Examples: obsidian, quartz

 They from by crystallization. This can happen two ways. Crystallization of lava or magma and the crystallization of dissolved minerals in water.  Crystallization: is the process by which atoms are arranged to form a material with a crystal structure.

 Minerals form as hot magma cools inside the crust, or as lava hardens on the surface. When these liquids cool to a solid state, they form crystals.  To get a larger crystal you need time for them to grow. If the magma has thousands of years you can get some vary large crystals.  If the molten material cools quickly then the crystals wont have time to grow so you end up with small or no crystals.

 A solution :is a mixture in which one substance is dissolved into another. When the elements and minerals that are dissolved in the solution leave then crystallization occurs.  This usually happens by evaporation then the solutes are left to crystallize,  Example: rock salt out at the great salt lake.  The other way is from hot water. Magma can heat water enough to dissolve metals into it. Then as it cools the metal will solidify usually in a vein.  Examples: silver and gold.

HHow do we use minerals? TThere are many different ways, depending on the mineral. If it is a metal or a precious gem then we can cut and from it into jewelry. If it essential to our life functions then we need to eat it. CCan anybody think of a mineral that is essential for us to live? EExamples: salt, Iron, calcium, and many others. CCan you think of any other uses? AAre there any questions? GGet ready for the quiz.

 1. What is a mineral?  2. Why are mineral important?  3. Who was the man that come up with the hardness scale?  4.How many crystal formations type are there?

 5. What is an essential element?  6. List 2 examples of essential minerals.  7. How many things are there that you must have to be a mineral?  8. List 3 of the thing that you must have to be a mineral.

 9. About how many minerals out there that scientist recognize?  10. What is fracture and cleavage?  11. Give an example of fracture.  12. Give an example of cleavage.