Rocks And Minerals

Color
The property color is the color or colors of the rock. Some minerals can be multiple colors like feldspar is usually pink or red but can be other colors. Other minerals can be colored by impurities.

Luster
Luster is the way light reflects off of a rock of mineral. Glassy luster looks like glass, metallic luster look like metal, and some rocks have a dull luster that looks like the rock lost some of it's shine.

Hardness
Minerals have different hardness'. You can test which rock or mineral is harder than the other by scratching the two rocks together and seeing which one scratched the other one. The Mohs scale can tell which rock is harder from 1-10. Since diamond is harder than quartz, diamond will scratch quartz. Diamond is the hardest rock, it has a hardness of 10.

Streak
Most minerals have many different colors but the streak for the mineral is always the same, quartz can be colored by impurities but the streak is always white. Sometimes, the rock's color is totally opposite of the streak, for example, pyrite is silver and the streak is black-green.

Shape
Shape is kind of hard to tell but some minerals have a definite shape. The crystal shape can help figure out what mineral it is. Crystals are classified by the shape and angles that they form by. For example, corundum looks like hexagons and fluorite looks like a cube. Scientists have created 6 different types of mineral shapes.

Rock Cleavage
Most minerals break in cool patterns. Minerals that break into smooth, flat surfaces have rock cleavage. Mica has rock cleavage because when it breaks it turns into flakes that are flat and smooth. Some minerals do not have rock cleavage because they usually shatter like glass of splinter like wood.

Rock Jokes

• What rock band does not sing? The Grand Canyon
• What did the lime stone say to the geologist? Don’t take me for granite!
• What is a rock’s favorite cereal?

Resources

• Scott Foresman Science book
• www.jokesbykids.com