Most minerals have the right to be characterized and classified by their distinctive physical properties: hardness, luster, color, streak, certain gravity, cleavage, fracture, and also tenacity.

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Hardness

The capability to withstand being scratched—or hardness—is one of the most beneficial properties for identifying minerals. Hardness is established by the capacity of one mineral to scrape another. Federick Mohs, a German mineralogist, created a hardness range (table 5) making use of a set of ten standard minerals. The scale arranges the minerals in order of boosting hardness. Each higher-numbered (harder) mineral will scratch any kind of mineral through a lower number (softer).

A unstable measure that mineral hardness can be made by assembling a kit of comfortable objects (table 6). A fingernail has actually a hardness ranging from 2 come 2.5, a penny is a tiny harder than 3, window glass arrays from 5.5 to approximately 6 in hardness, and also a knife tongue is typically in the selection of 5 to 6.5.

HardnessMineralCommon ar test
1TalcEasily scratched with a fingernail
2GypsumScratched by a fingernail (2.5)
3CalciteScratched by a penny (3)
4FluoriteDifficult to scratch by a pond (4); scratched easily by a knife (5)
5ApatiteDifficult to scrape with a knife (>5); barely scratches glass (5.5)
6FeldsparScratched through a steel file (6.5); conveniently scratches glass
7QuartzScratches a steel file and glass
8TopazDifficult to test in the field
9CorundumDifficult to check in the field
10DiamondDifficult to test in the field

Creating a Mineral Hardness test Kit

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A mineral hardness test kit can be easily produced from typical household or hardware items (table 6). Parental should help children make the kit. Wear safety and security glasses and also gloves once cutting class. All pieces in the hardness test kit need to be compared to one another and details minerals through a recognized hardness.

Approximate HardnessItem
1Blackboard Chalk
2.5Fingernail
3Copper penny
4Common nail
5.5-6.5Pocket knife
5.5Window glass (2 inch square; usage caution making this scrape plate. Ice the edge of the glass v duct tape. You may be able to get this reduced at a neighborhood hardware store.)
6.5Steel record or tempered steel. Shot to discover an old, broken or worn flat file

Luster

Luster is just how a mineral mirrors light. The state metallic and also nonmetallic define the simple types of luster. Table 7 perform the most typical terms offered to define luster and an example of a matching mineral. Part minerals that don"t exhibition luster are described as "earthy," "chalky," or "dull."

Color

One of the most obvious properties that a mineral is color. Shade should be taken into consideration when identify a mineral, but should never be offered as the significant identifying characteristic.

Streak

Streak is the shade of the powdered mineral, i beg your pardon is usually an ext useful because that identification 보다 the shade of the entirety mineral sample. Rubbing the mineral on a streak key will produce a streak. A streak plate deserve to be do from the unglazed ago side the a white porcelain restroom or kitchen tile. Part minerals won"t streak because they room harder than the streak plate.

Specific Gravity

Specific gravity is the ratio in between the mass (weight) of a mineral and the mass (weight) that an equal volume that water. A mineral"s specific gravity (SG) have the right to be determined by dividing its load in wait by the load of an equal volume of water. For instance, quartz with a density of 2.65 is 2.65 times as hefty as the same volume the water.


Cleavage

The means in i m sorry a mineral breaks follow me smooth flat planes is called cleavage. This breaks occur along plane of weakness in the mineral"s structure. However, if a mineral breaks along an rarely often rare surface, the does not have cleavage.

Fracture

When a mineral division irregularly, the breaks are called fractures. The breaks deserve to be defined as grainy, hackly (jagged), conchoidal (curved), or splintery.

Tenacity

How fine a mineral resists wrong is well-known as tenacity. Tenacity is defined using this terms:

Brittle - Mineral crushes come angular pieces (quartz).Malleable - Mineral deserve to be modification in form without breaking and can be planarization to a thin sheet (copper, gold).Sectile - Mineral have the right to be cut with a knife right into thin shavings (talc).Flexible - Mineral bends however doesn"t gain back its shape once released (selenite, gypsum).Elastic - Mineral bends and regains its original shape once released (muscovite and also biotite mica).

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Other Diagnostic Characteristics

Other characteristics may be valuable in identifying some minerals:

Transparency - Objects space visible once viewed v a mineral.Translucency - Light, but not one image, istransfer through a mineral.Opaqueness - No light is transmitted, even on the thinnest edges.Taste - Taste have the right to be provided to help identify part minerals, such together halite (salt).Acid reaction - object reacts come hydrochloric acid. The most distinguishing characteristic that calcite is that it effervesces when hydrochloric mountain is applied. Dolomite reflects a reaction on a freshly broken or powdered surface. Experimentation for calcite, limestone, or dolomite calls because that 10% hydrochloric acid, but strong white vinegar have the right to be substituted because that the acid.Magnetism - Magnetism is a distinguishing characteristic of magnetite.Crystal shape - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Part crystal forms are portrayed below.

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