Minerals

4 Pages
77 Views
Unlock Document

Department
Geological Sciences and Geological Engineering
Course
GEOL 104
Professor
Michael T.Mc Bride
Semester
Fall

Description
Minerals: The Building Blocks of Life  A mineral must exhibit the following characteristics to be classified as such:  It must occur naturally  Solid at surface temperatures and pressures  Orderly internal structure (atoms arranged in a definite pattern)  Definite chemical composition that can vary within specified limits  Usually inorganic (some mineral formation can be mediated by biologic processes)  A rock is any solid mass of mineral matter that occurs naturally as part of our planet  Limestone is composed of impure masses of the mineral calcite  Granite is composed of aggregates of different minerals (quartz, hornblende, and orthoclase feldspar)  aggregate implies the minerals are joined in a way that retains the properties of each individual mineral  Some rocks are composed of non-mineral matter such as the volcanic rocks obsidian and pumice which contain noncrystalline glassy substances  Coal is composed of organic matter  Halite, composed of sodium and chloride (common salt) form a cubed shape internal structure which allows for salt crystals  Polymorphic minerals are minerals that share the same elements but have different properties:  Diamonds and Graphite both consist exclusively of carbon but have drastically different properties Property: Diamond: Graphite: Hardness 10 1 Cleavage* 4 directions 1 direction Lustre adamantine metallic Other High pressure needed Excellent lubricant *Cleavage is how a mineral breaks along planar surfaces  The carbon atoms in Diamond each are strongly bonded to 4 other carbons and form a 3D framework that accounts for the minerals hardness  The carbon atoms in Graphite share 3 bonds with other carbons, forming a layered sheet with strong bonds within a sheet but weak bonds between sheets  allows sheets to slide past each other easily, making the mineral a good lubricant  Physical properties of Mineral Identification include:  Shape: how a crystal grows (ie. Quartz forms well-developed hexagonal crystals with pyramid shaped ends)  Lustre: appearance/quality of light reflected (ie. metallic, non-metallic, pearly, glassy/vitreous, silky, resinous, earthy/dull)  Colour: minerals can have a single colour or multiple forms with varying colours (ie. Quartz can be purple in amethyst, pink in rose quartz, brown/black, or yellow/orange in citrine)  Streak: colour of a mineral in its powdered form or rubbed across unglazed porcelain (ie. reddish brown streak in Hematite is different than its colour)  Hardness: measure of resistance to abrasion/scratching using the Mohs scale  Cleavage: how a mineral breaks along planar surfaces, or areas of weak bonding  can occur at different angles, for example, calcite has 3 directions of cleavage not at 90°, fluorite has 4 directions, and amphibole has 2 not at 90°  Fracture: minerals with a consistent strength of bonds lack the ability to cleave along planar surfaces, and therefore break a certain way (ie. Quartz fractures to form smooth curves resembling a seashell, known as a conchoidal fracture)  most minerals fracture unevenly into irregular fragments  Specific Gravity: ratio of the weight of a mineral to the weight of an equal volume of water (heavier minerals have heavier specific gravity, such as Galena, which has a specific gravity of 7.5)  Other Properties: includes transparency (Calcite demonstrates double refraction), smell (sulfur-bearing minerals may smell like rotte
More Less

Related notes for GEOL 104

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit