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

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The ability to resist being scratched—or hardness—is among the most useful properties for identifying minerals. Hardness is established by the ability of one mineral to scratch another. Federick Mohs, a German mineralogist, developed a hardness range (table 5) using a collection of ten typical minerals. The scale arvarieties the minerals in order of enhancing hardness. Each higher-numbered (harder) mineral will certainly scrape any mineral through a reduced number (softer).

A unstable meacertain of mineral hardness deserve to be made by assembling a kit of handy objects (table 6). A fingernail has a hardness varying from 2 to 2.5, a penny is a tiny harder than 3, home window glass varieties from 5.5 to approximately 6 in hardness, and also a knife blade is mainly in the array of 5 to 6.5.

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

Creating a Mineral Hardness Test Kit

A mineral hardness test kit have the right to be quickly produced from widespread household or hardware items (table 6). Paleas need to assist kids make the kit. Wear safety glasses and gloves when cutting class. All pieces in the hardness test kit must be compared to one one more and particular minerals via a known hardness.

Approximate HardnessItem
1Blackboard Chalk
3Copper penny
4Usual nail
5.5-6.5Pocket knife
5.5Window glass (2 inches square; use caution making this scrape plate. Tape the edges of the glass with duct tape. You may have the ability to obtain this reduced at a neighborhood hardware store.)
6.5Steel file or tempered steel. Try to find an old, damaged or worn flat file


Luster is exactly how a mineral mirrors light. The terms metallic and nonmetallic explain the standard forms of luster. Table 7 lists the many common terms supplied to define luster and also an example of a corresponding mineral. Some minerals that do not exhibit luster are referred to as "earthy," "chalky," or "dull."


One of the a lot of noticeable properties of a mineral is color. Color need to be taken into consideration once identifying a mineral, but have to never before be supplied as the significant identifying characteristic.


Streak is the color of the powdered mineral, which is normally even more helpful for identification than the shade of the entirety mineral sample. Rubbing the mineral on a streak plate will certainly produce a streak. A streak plate have the right to be made from the unglazed earlier side of a white porcelain bathroom or kitchen tile. Some minerals will not streak because they are harder than the streak plate.

Specific Gravity

Specific gravity is the ratio between the mass (weight) of a mineral and the mass (weight) of an equal volume of water. A mineral"s particular gravity (SG) can be identified by splitting its weight in air by the weight of an equal volume of water. For circumstances, quartz via a thickness of 2.65 is 2.65 times as hefty as the exact same volume of water.


The way in which a mineral breaks alengthy smooth level planes is referred to as cleavage. These breaks happen alengthy planes of weakness in the mineral"s framework. However, if a mineral breaks alengthy an irregular surface, it does not have actually cleavage.


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


How well a mineral resists breakage is known as tenacity. Tenacity is defined making use of these terms:

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

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Other Diagnostic Characteristics

Other features may be helpful in identifying some minerals:

Transparency - Objects are visible as soon as regarded via a mineral.Translucency - Light, but not an image, is transmitted with a mineral.Opaqueness - No light is transmitted, even on the thinswarm edges.Taste - Taste deserve to be offered to aid recognize some minerals, such as halite (salt).Acid reactivity - Object reacts to hydrochloric acid. The the majority of separating characteristic of calcite is that it effervesces as soon as hydrochloric acid is applied. Dolomite shows a reactivity on a freshly broken or powdered surchallenge. Testing for calmention, limerock, or dolomite calls for 10% hydrochloric acid, however strong white vinegar deserve to be substituted for the acid.Magnetism - Magnetism is a differentiating characteristic of magnetite.Crystal form - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Some crystal shapes are illustrated listed below.