Most minerals have the right to be characterized and classified through their distinct 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 among the most useful properties for identifying minerals. Hardness is identified by the capability of one mineral to scratch another. Federick Mohs, a German mineralogist, created a hardness scale (table 5) utilizing a collection of ten conventional minerals. The scale arranges the minerals in stimulate of increasing hardness. Every higher-numbered (harder) mineral will certainly scratch any kind of mineral v a lower number (softer).

A rough measure that mineral hardness have the right to be do by assembling a kit of handy 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 ranges from 5.5 to approximately 6 in hardness, and also a knife blade is usually in the variety of 5 come 6.5.

HardnessMineralCommon field test
1TalcEasily scratched v 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); right scratches glass (5.5)
6FeldsparScratched by a steel document (6.5); easily scratches glass
7QuartzScratches a steel document and glass
8TopazDifficult to test in the field
9CorundumDifficult to check in the field
10DiamondDifficult to check in the field

Creating a Mineral Hardness test Kit

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A mineral hardness check kit have the right to be easily developed from usual household or hardware items (table 6). Parental should aid children do the kit. Wear security glasses and also gloves as soon as cutting class. All piece in the hardness test kit must be compared to one one more and certain minerals through a known hardness.

Approximate HardnessItem
1Blackboard Chalk
2.5Fingernail
3Copper penny
4Common nail
5.5-6.5Pocket knife
5.5Window glass (2 inch square; use caution make this scrape plate. Ice cream the edges of the glass through duct tape. Girlfriend may be able to get this reduced at a local hardware store.)
6.5Steel file or tempered steel. Shot to uncover an old, broken or worn level file

Luster

Luster is just how a mineral reflects light. The terms metallic and nonmetallic explain the straightforward types that luster. Table 7 lists the most typical terms provided to define luster and an example of a equivalent mineral. Part minerals the don"t exhibition luster are referred to as "earthy," "chalky," or "dull."

Color

One of the most noticeable properties that a mineral is color. Shade should be thought about when identify a mineral, however should never be used as the major identifying characteristic.

Streak

Streak is the color of the powdered mineral, i beg your pardon is usually an ext useful for identification 보다 the color of the whole mineral sample. Rubbing the mineral on a streak bowl will develop a streak. A streak plate deserve to be made from the unglazed ago side that a white porcelain toilet or kitchen tile. Some minerals won"t streak since they are harder than the streak plate.

Specific Gravity

Specific gravity is the ratio in between the massive (weight) the a mineral and the mass (weight) the an equal volume the water. A mineral"s details gravity (SG) deserve to be determined by separating its weight in waiting by the weight of an equal volume of water. Because that instance, quartz with a thickness of 2.65 is 2.65 times as hefty as the exact same volume the water.


Cleavage

The way in i beg your pardon a mineral breaks follow me smooth flat planes is called cleavage. These breaks take place along plane of weakness in the mineral"s structure. However, if a mineral breaks along an irregular surface, the does not have cleavage.

Fracture

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

Tenacity

How fine a mineral resists breakage is well-known as tenacity. Tenacity is explained using these terms:

Brittle - Mineral crushes come angular fragments (quartz).Malleable - Mineral have the right to be modified in form without breaking and can be flattened to a thin sheet (copper, gold).Sectile - Mineral can be reduced with a knife into thin shavings (talc).Flexible - Mineral bends but doesn"t reclaim its shape as soon as released (selenite, gypsum).Elastic - Mineral bends and also regains its initial shape as soon as released (muscovite and also biotite mica).

See more: Salt And Sugar Crystals Look The Same When Viewed With A Magnifying Glass.

Other Diagnostic Characteristics

Other qualities may be valuable in identifying part minerals:

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

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