mineral properties2

Mineral IDHow to identify a mineral by its properties

Baker 7th grade science

Today you will learnWhich mineral properties are most important in identification.How mineral are identified by their properties.


A minerals appearance helps identify it.In order to identify a mineral, you need to observe it properties characteristics that help identify it.There are 5 main properties that we use to identify. There are many minor properties that can also help id a mineral.


Mineral Property #1 Color & StreakColor is the first thing someone notices when they view a mineral.

Color is also one of the big reasons that attract people to minerals. Generally speaking, color is not a good property to be used in the identification of minerals. It is usually the first property to confuse a novice collector into making an incorrect identification. Many minerals have different colors and some minerals' colors are identical to other minerals' colors.


Mineral Property #1 Color & StreakStreak is closely related to color, but is a different property because the color of the mineral may be different than the color of the streak. Streak is actually the color of the powder of a mineral. It is called streak because the proper way to test for streak is to rub a mineral across a tile of white unglazed porcelain and to examine the color of the "streak" left behind.


Mineral Property #1 Color & StreakPyrite (known as "Fool's Gold") is always brassy yellow when found in crystals, even broken crystals, of any size; but when powdered, produces a black streak. Gold's streak, by the way, is yellow!Hematite's streak is blood-redGalena's streak is lead gray


Mineral Property # 2LusterA minerals luster is the way in which light reflects from the surface. The two major types of luster are metallic & nonmetallic.


Mineral Property # 2LusterSome other ways to describe luster areDull - just a non-reflective surface of any kind Earthy - the look of dirt or dried mud Fibrous - the look of fibers Greasy - the look of grease Gumdrop - the look a sucked on hard candy Metallic - the look of metals Pearly - the look of a pearl Pitchy - the look of tar Resinous - the look of resins such as dried glue or chewing gum Silky - the look of silk, similar to fibrous but more compact Submetallic - a poor metallic luster, opaque but reflecting little light Vitreous - the most common luster, it simply means the look of glass Waxy - the look of wax


Quick CheckGet out your whiteboard and quickly answer the following:What is the first thing someone notices about a mineral?What do we call the color of the powdered mineral?Which is more reliable: streak or color?


Mineral Property # 3How a mineral breaksWhen a mineral breaks it does so either by fracturing or by cleaving.Cleavage is the tendency of a mineral to break along flat surfaces. Crystal cleavage is a smooth break producing what appears to be a flat crystal face. Fracture is the tendency of a mineral to break into irregular pieces.


Mineral Property #4HardnessA minerals hardness is its resistance to being scratched. A scale known as the Mohs scale is often use


Mohs Scale


Mineral Property #5DensityEach mineral has a specific density.Density is the mass of a given space or in scientific terms the mass per unit of volume.For example, if you have two minerals of the same size one might be heavier than the other. The galena will be three times heavier than the same size of quartz.


Mineral Property #5DensityGeologists measure density by the following:First they use a balance to determine the mass of a sample.Second, they place the mineral in water to see how much water it displaces. The volume of displace water = the volume of the sampleThird they use the following formula:Density = Mass/Volume


Brain CheckGet out your whiteboard and quickly answer the following:If you break a mineral and it breaks into cubes, is it fracture or cleavage? Why?If you break a mineral with a hammer and it falls apart into a million different pieces, is it fracture or cleavage? Why?Name three things you can scratch talc with.What is the formula for density?


Some minerals have specific propertiesFluorescence: some minerals glow when exposed to ultraviolet lightMagnetic: Some minerals are attracted to magnetsAcid: Some minerals react with acid by bubbling


SLCDFHSome Llamas Climb Down Funny HillsStreakPowdered ColorLusterHow shinyCleavageBreaks in sheets or blocksDensityHow much mass in a given volumeFractureJust crumbles & breaksHardnessCan be scratched by


mineral properties2

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