Mineral Properties & Identification

The story of minerals so far…. Minerals formed from elements that originated in exploding stars, made a nebula and then formed our solar system Minerals are solid, naturally occurring, inorganic, made of chemical elements and have an internal arrangement of atoms (crystal structure) Native minerals are made of 1 element: gold, sulfur, iron Top elements that make up the Earth’s crust are: oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium Most minerals are compounds: NaCl, CaCO3 SiO2 A rock is a mixture of 1 or more minerals: granite Limestone is made of only one mineral – calcite.

Properties used to Identify Minerals Color Odor Shiny or dull (Luster) Hardness (scratches) Streak color (on streak plate) Solubility in water Dissolve in water or react in acid Cleavage (split or shatter when hammered) Review these properties after students have had a chance to sort and group minerals into piles by characteristics

More properties to I.D. minerals Optical properties: double refraction Magnetic Heavy (specific gravity) Crystal shape Fluorescent Taste? Radioactive Crystal shape is next section, obviously we won’t test radioactivity

In each Mineral I.D. Lab bag: 8 minerals 1 Hand lens 1 yellow 1 Penny 2 clear 1 Glass plate 2 pink 2 Streak plates 1 dark red 1 magnet 1 flat 1 Nail 1 gold

Mineral I.D. Lab

Physical Properties of Minerals Color: light or dark, yellow, gold, pink…. Luster: metallic, Non-metallic: dull, glassy, vitreous, pearly, adamantine Light Interaction: Opaque: not allowing light to pass through Translucent: “cloudy”; some light passes through but not able to see clear detail Transparent: allows light to pass through and detail can be seen clearly

Streak The color of the mineral in its powdered form. Rubbing the mineral on a streak plate. Streak is more reliable than color: Streak is a consistent property of a mineral. Metallic minerals generally have a dark streak, Non-metallic mineral do not Two different colored forms of the SAME mineral: SAME colored streak

Hardness Mohs scale of hardness Relative scale: comparing the hardness of a mineral to a known object. 1-10 Diamond being the hardest 10 Talc is the softest 1

Quartz (glass) fractures and shatters into irregular-shaped pieces with no flat planes Cleavage: the tendency of a mineral to break along flat planes of weak bonding Halite will cleave into many smaller pieces each with 3 planes at 90°

Three examples of perfect cleavage – 3 flat planes (sides) fluorite, halite, and calcite

sulfur calcite Halite hematite feldspar Pyrite Mica Quartz Name Color Luster Light Interaction Streak Hard-ness Cleavage Smell Sol. water acid 1 Yellow Dull Opaque 1-2 none Rotten Egg! IS 2 Gold, metallic, shiny opaque black 6 SS? 3 white Pearly, flat Transparent translucent 2-3 Perfect! 1 direction peels 4 Clear Double refraction None perfect YES! FIZZ 5 Clear, white Shiny, Tastes salty 2-2.5 3 direction 90° angle Yes! dis- solves Dark red-brown dull Red-brown 3-4 None or earthy SS 7 Salmon pink Good 2 direction 8 Pink, clear glassy fractures concoidal sulfur Pyrite Mica (Muscovite) calcite Halite (Salt) You can do the first one together as a class to go through the lab procedures. hematite feldspar Quartz

Smells like rotten eggs Mineral Specimen Number   Color Luster Light interaction Streak color Hardness number Cleavage Or Fracture Soluble in water Solubility in acid Other Properties: Magnetism, Fluorescence Mineral name page 700- 701 1 yellow dull opaque 1-2 fracture  insoluble Smells like rotten eggs 2 3 4 5 6 7 8 sulfur

Mineral Flow Chart in your notebooks copy the chart below Color? dark or light _______________ Luster? Metallic or non-metallic ________ Streak? Black, brown or reddish________ Harder than glass? __________________ Cleavage? Yes, no cleavage, 1,2,3,4 planes Mineral Name _____________