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

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The capacity to withstand being scratched—or hardness—is one of the most advantageous properties because that identifying minerals. Hardness is identified by the capability of one mineral to scrape another. Federick Mohs, a German mineralogist, produced a hardness scale (table 5) utilizing a collection of ten traditional minerals. The range arranges the minerals in bespeak of increasing hardness. Every higher-numbered (harder) mineral will scratch any kind of mineral through a lower number (softer).

A rough measure of mineral hardness deserve to be make by assembling a kit of handy objects (table 6). A fingernail has actually a hardness ranging from 2 to 2.5, a penny is a tiny harder than 3, window glass varieties from 5.5 to around 6 in hardness, and a knife tongue is generally in the variety of 5 to 6.5.

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

Creating a Mineral Hardness test Kit

A mineral hardness test kit can be easily produced from typical household or hardware item (table 6). Parental should assist children make the kit. Wear security glasses and also gloves as soon as cutting class. All pieces in the hardness test kit should be compared to one one more and certain minerals with a recognized hardness.

Approximate HardnessItem
1Blackboard Chalk
3Copper penny
4Common nail
5.5-6.5Pocket knife
5.5Window glass (2 customs square; usage caution do this scrape plate. Tape the edges of the glass v duct tape. Girlfriend may have the ability to get this reduced at a regional hardware store.)
6.5Steel paper or tempered steel. Shot to discover an old, broken or worn flat file


Luster is exactly how a mineral shows light. The state metallic and also nonmetallic explain the straightforward types of luster. Table 7 list the most usual terms supplied to explain luster and an example of a equivalent mineral. Some minerals that don"t exhibit luster are referred to as "earthy," "chalky," or "dull."


One that the most noticeable properties the a mineral is color. Color should be taken into consideration when identify a mineral, yet should never be used as the significant identifying characteristic.


Streak is the shade of the powdered mineral, i beg your pardon is usually more useful because that identification than the shade of the whole mineral sample. Rubbing the mineral ~ above a streak bowl will produce a streak. A streak plate deserve to be make from the unglazed ago side the a white porcelain restroom or kitchen tile. Some minerals won"t streak because they space harder 보다 the streak plate.

Specific Gravity

Specific heaviness is the ratio in between the fixed (weight) that a mineral and the massive (weight) that an equal volume the water. A mineral"s certain gravity (SG) deserve to be figured out by dividing its load in wait by the weight of an equal volume the water. Because that instance, quartz v a thickness of 2.65 is 2.65 times as hefty as the same volume that water.


The means in i m sorry a mineral breaks follow me smooth flat planes is dubbed cleavage. These breaks take place along airplane of weakness in the mineral"s structure. However, if a mineral breaks follow me an rarely often rare surface, that does not have actually cleavage.


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


How well a mineral resists wrong is well-known as tenacity. Tenacity is described using these terms:

Brittle - Mineral crushes to angular fragments (quartz).Malleable - Mineral can be amendment in shape without breaking and also can be planarization to a slim sheet (copper, gold).Sectile - Mineral deserve to be reduced with a knife right into thin shavings (talc).Flexible - Mineral bends but doesn"t gain back its shape when released (selenite, gypsum).Elastic - Mineral bends and regains its original shape as soon as released (muscovite and biotite mica).

See more: What Force Holds The Lattice Structure In Place In A Crystal ?

Other Diagnostic Characteristics

Other attributes may be advantageous in identifying part minerals:

Transparency - Objects space visible when viewed through a mineral.Translucency - Light, yet not one image, is transmitted v a mineral.Opaqueness - No irradiate is transmitted, also on the thinnest edges.Taste - Taste deserve to be used to help identify some minerals, such as halite (salt).Acid reaction - object reacts come hydrochloric acid. The most distinguishing characteristic the calcite is the it effervesces when hydrochloric mountain is applied. Dolomite shows a reaction on a freshly damaged or powdered surface. Trial and error for calcite, limestone, or dolomite calls for 10% hydrochloric acid, but solid white vinegar can be substituted because that the acid.Magnetism - Magnetism is a separating characteristic of magnetite.Crystal shape - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Some crystal shapes are shown below.