Identifying the Characteristics and Physical Properties of Minerals


Clear quartz showing crystal shape
What is a Mineral?
All the rocks and minerals of Earth's crust consist of elements.  An element is a substance that cannot be broken into simpler substances by ordinary chemical means. A mineral is a naturally occurring inorganic solid with a definite chemical composition and an orderly arranged atomic structure.  Most minerals are compounds (two or more elements chemically combined).  More than 90 percent of the minerals in Earth's crust are compounds containing oxygen and silicon, the two most abundant elements.

How Minerals Form
Minerals form in several ways.  Many form out of magma (molten rock), in which atoms and ions move freely.  As magma cools, the atoms and ions move closer together and form chemical bonds that create compounds.  The rate at which magma cools determines the size of the minerals grains (crystals) that form.  Mineral forming processes can be gradual and lengthy. 

Amethyst Crystal showing crystal shape
Some types of minerals form as water containing dissolved ions slowly evaporates.  For example, Halite (rock salt) forms when sea-water evaporates.  As evaporation occurs, sodium and chlorine ions combine and bond to form the mineral Halite.

Identifying Minerals by Inspection
The most common way of revealing most minerals is through visual inspection and observing the physical properties of minerals.  These physical properties are:
  • luster
  • color
  • hardness
  • streak
  • cleavage or fracture
  • crystal shape, and
  • specific gravity
These physical properties must be considered together in order to reveal the identity of a mineral.  Rarely is it possible to identify a mineral using a single property. For further information on rocks and minerals go to rocksforkids.com;

Homework:
Due: Friday, November 13, 2015
Review book, read Topic 11, pages 218-222. Do review questions 1-8  on pages 222-223.

Comments

Post a Comment

Popular posts from this blog

Rock Cycle

Image
The rock cycle is a model of the natural changes that occur in rocks and rock materials on the earth. The diagram to the right distinguishes between those processes that take primarily at Earth's (external processes) and those that take place within the Earth (internal processes).  Internal processes, such as compression and heating require the conditions of extreme temperature and pressure that occur deep within the Earth. The rock cycle illustrates several important principals of geology. First, nearly all rocks are made from the remains of other rocks (coal and other organic sedimentary rocks are important exceptions).  Second, rocks are classified on the basis of their origin.  Finally, there are a variety of ways that rocks can change in response to changing conditions at the surface or within Earth. Homework  due Wednesday, April 6, 2011 Review Book:  read pages 55-56; do questions 54-60 on pages 56-57, and questions 1-10 on pages 59-60.
Read more

Weather Map Project

Image
In the past two weeks, we have been studying the properties of the atmosphere and the different weather variables. This week we will begin constructing weather maps.  We will also do a weather map project. The details are as follows: Project Due Date :  Friday, February 18, 2011 Task: Your assignment is to construct a weather map, for a seven day period, across the United States. Criteria : You may select the weather for a seven day period of your choosing. The project must be illustrated on poster paper and may include a typed report. The project must include the following items: o Title of Assignment o Two weather maps that track the changes in weather for the seven day period (from either newspaper or internet). o Map must include a general description of the weather patterns, for example, a description of air masses likely to create fronts (cP, continental polar, mT, marine tropical, etc.). o Indicate on map where unstable weather is occurring across the nation (precipitat
Read more

The Transportation of Weathered Materials

Image
Broken fragments of weathered rock are called sediments . These sediments are often carried or transported from their place of origin to another location. Erosion is the transportation of sediments most often done by water, wind and glaciers. The force of gravity drives most forms of erosion. For example, a weathered rock on a cliff is pulled by gravity, causing it to fall to the bottom of the cliff. Continued erosion, aided by wind and water, moves the sediment downslope away from the cliff. This week we will focus on the agents of erosion and in particular, the characteristics of a stream or river that affect its ability to erode sediment. Homework # 3 : Due Wednesday, February 25, 2009 Textbook: read pages 280-284. Review book: read pages 85-88; do questions 24-37.
Read more