MINERAL IDENTIFICATION

WHAT IS MINERALOGY? Mineralogy is the study of _______________ __________________ ___________________ ____________________ ____________________ ____________________ ____________________ ____________________

ROCK FORMING MINERALS There are nearly _________ minerals but there are only _______ That are at all common. Elements like gold and diamond are rare.

COMMON MINERALS The most common minerals are _______, _________, _________, and ______________ These and others make up most of the minerals in the Earth’s crust also known as __________ __________________

WHAT IS THE DIFFERENCE BETWEEN A ROCK AND A MINERAL? The difference between a rock and mineral are the following: ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ ____________________

HOW ARE MINERALS IDENTIFIED? Geologists look at the physical and chemical properties and simple tests to help them identify each mineral. These are: a.___________________ b.____________________ c.________________ d.____________________ e. __________________ f.____________________ g.____________________ h.____________________ i_____________________ j.____________________

COLOR One of the most noticeable characteristics of a mineral. However, it is not the most reliable. The color of the minerals is sometimes caused by the presence of trace elements or compounds within the mineral.

QUARTZ Quartz occurs in a variety of colors. These different colors are the result of different trace elements in the quartz samples. Amethyst and citrine contain different amounts of iron Rose quartz contains manganese and titanium

CRYSTAL FORM Some minerals form such distinct crystal shapes that they are immediately recognizable. Halite always forms perfect cubic crystals As you have found not all minerals form perfect crystal shapes so, to identify a crystal solely based on crystal formation is rare.

LUSTER Luster is the way ____ ____________________ ____________________ ____________________ There are two types of luster : __________________ And

METALLIC LUSTER ________, __________, ___________ , _______________ ___________ , _______________ All have shiny surfaces and reflect light. However, not all metallic minerals have metallic luster _____________ is a mineral with a metallic luster but is not a metal

NONMETALLIC LUSTER Minerals with nonmetallic luster , like calcite Gypsum, sulfur and quartz do not shine like metals. Nonmetallic luster are described as ______, _________, _________ Differences in luster are due to the differences in the ___________ _____________ of the minerals. Identifying nonmetallic luster maybe a bit difficult . It is a good practice to use another physical characteristic with luster in identifying a mineral.

HARDNESS One of the most reliable tests for identifying a mineral. _________is a measure Of how easily a mineral can be scratched. German Geologist Friedrich Mohs developed the scale by which an unknown mineral’s hardness can be compared to 10 known minerals. The ten minerals selected were the most easily recognized and most common in nature with the exception of diamond.

THE SCALE The scale ranges from 1-10 1 is the softest mineral (Talc) and can be scratched with a fingernail – To 10 diamond which can scratch all the minerals on the list A mineral that can be scratched by your fingernail has a hardness of 2 or less. A mineral that cannot be scratched by your fingernail and cannot scratch glass has a hardness value between 2.5 and 5.5 A mineral that can scratch glass has a hardness value of 5.5 or greater

MATERIALS USED TO CONDUCT THE HARDNESS TEST Fingernail - 2.5 Copper penny – 3.5 Iron nail- 4.5 Glass-5.5 Steel file – 6.5 Streak plate - 7 If there is more than one mineral in the sample it is a good idea to test more than one area of the sample. This way you can be sure you are testing the hardness of the mineral you are studying.

CLEAVAGE AND FRACTURE Atomic arrangement will also determine how a mineral will break. Minerals break where atomic bonding is weak. A mineral that splits relatively easy and evenly along one or more flat planes exhibits ____________ An example is mica it breaks in one direction. It breaks in sheets because of weak atomic bonds.

FRACTURE Quartz breaks unevenly along jagged edges because it has tightly bonded atoms. Minerals that break with rough or jagged edges are said to _________________ Flint , jasper also exhibit fracture with arclike patterns that resemble a clamshell . This is a good property in identfying minerals.

STREAK A mineral rubbed across an unglazed plate will sometimes leave a colored powered streak on the surface of the plate. ___________ is the color of the mineral when it is broken up into a powder. The streak of a nonmetallic mineral is usually ____________. Streak is most useful when identifying a metallic mineral. Sometimes the streak does not match the metallic mineral’s external color Hematite is a good example

HEMATITE Hematite that forms from weathering (exposed to air and water) is a rusty red color and has an earthy feel. Hematite that forms from magma is silver and metallic in appearance . Both however, show a red streak when tested. This is another reason streak cannot be the sole test.

SPECIAL PROPERTIES Several minerals exhibit special properties that can easily identify them Calcite (Iceland Spar) Double refraction Calcite- Effervescence Magnetite- Magnetism Fluorite/Calcite- Fluorescence

TEXTURE Texture describes how a mineral feels to the touch. This is also difficult because this can be somewhat subjective like luster. Texture of a mineral can be described as smooth, ragged, greasy, or soapy.

SPECIFIC GRAVITY/ DENSITY Sometimes two minerals of the same size have different weights . Differences in weight is the result of differences in densities. Density reflects the atomic mass and structure of the mineral Because density is not dependent on the size or shape . Density at times can be very hard to determine .

SPECIFIC GRAVITY The most common measure of density in minerals is __________ ____________________ It is the ratio of the mass of a substance to the mass of an equal volume of water at 4 degrees C.

SUMMARY The most reliable way to identify a mineral is by using a combination of several test.