Earth Science Daily Challenge, 11/12Minerals crystals can be tiny or very

large. What kinds of things might control how big a given crystal grows?

What properties of mineralsare used to identify them?

• Magnetism– some minerals have enough iron to attract a

magnet or act as a compass• Fluorescence

– some minerals “glow” with unusual colors under ultraviolet radiation

• Chemical reaction with acid– carbonate minerals (like calcite) “fizz” when

exposed to weak acid• Optical Properties

– Calcite makes “double vision,” etc.

• Naturally Occurring, Inorganic Solid with a Fixed Chemical Composition and a Crystal Structure

What is a MINERAL?

How do minerals form?• Mineral crystals grow when conditions

are right for atoms and molecules to link up in 3-dimensional repeating patterns.

Earth Science Daily Challenge, 11/18In today’s lab, we will investigate igneous

minerals formed from cooling magma/lava.

Hypothesize: How will the igneous minerals be different from the sedimentary minerals of

the previous lab?

What are the “right conditions” for mineral formation?

• Minerals crystallize from solutions (mixtures of water and dissolved solids.)–Hot water cools and deposits mineral

crystals. (black smokers, hot springs, etc.)–Water evaporates, leaving mineral crystals

behind. (dry lakes, salt flats, caves, veins)• Minerals crystallize from cooling molten

rock (magma or lava) OR recrystallization.

What determines the size of a mineral crystal? In other words, how many atoms can link up?

http://toprocks.net/Pics21/A9399XSCE2.jpg

Crystals can grow as long as there are MORE ATOMS available, TIME for them to get into the crystal structure, and SPACE to grow.

Mineral Classification Systems• Crystal System

– cubic, hexagonal, monoclinic, etc.• Composition

– silicates, carbonates, halides, sulfates, etc.• Use

– metal ores, gems, aggregate, etc.• Genesis (origin / how they formed)

– igneous minerals (cooled magma/lava)– sedimentary minerals (deposited by water)– metamorphic minerals (changed by heat/pressure)