minerals Week 3 term 3

Size is everything

What are mierals? 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.

Other thing’s needed to be a mineral Solid, a mineral is always a solid. Chrystal structure, the particles of the mineral line up in a pattern the repeats over and over again. Definite chemical composition, this means the 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.

How to identify minerals. 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.

The ways!! Color: the color of an mineral can easily seen but is not a good way to positively identify a mineral. There are few mineral that have a vary 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.

The ways!! 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.

The ways continued!!! 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 same size you can tell the one with more density because it will be heaver. Example: galena is much more dense that quartz. The same size sample of galena will weigh three time as much as the quartz.

The ways still continued!!! 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 then 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.

Hardness contined

Hardness still continued!! 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.

Crystal system 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 and fracture 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

This examples of rock cleavage

This is examples of rock fracture

How minerals form. 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 from lava and magma 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.

Minerals from solution 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.

Minerals uses. How do we use minerals? 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. Can you think of any other uses? Are there any questions? Get ready for the quiz.

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?