domingo, 19 de septiembre de 2010

Vocabulary 13

mineral:a  solid material of Earth´s crust with a definite composition.
Luster: the way light bounces off mineral´s surface.



streak:the color of the powder left when a mineral is rubbed against a hard,rough surface.




hardness:how well a mineral resists scratching

cleavage: the tendency of a mineral to break along flat surfaces.

ore:a mineral containing a usefull substance.

gem:a mineral valued for being rare and beautiful.


nonrenewable resource: a resource that cannot be replaced within a short period of time or at all.


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