Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, details gravity, cleavage, fracture, and tenacity.

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Hardness

The ability to stand up to being scratched—or hardness—is one of the most helpful properties because that identifying minerals. Hardness is figured out by the capacity of one mineral to scratch another. Federick Mohs, a German mineralogist, developed a hardness scale (table 5) making use of a collection of ten conventional minerals. The scale arranges the minerals in stimulate of boosting hardness. Each higher-numbered (harder) mineral will certainly scratch any kind of mineral with a reduced number (softer).

A turbulent measure that mineral hardness have the right to be make 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 little harder than 3, home window glass ranges from 5.5 to roughly 6 in hardness, and also a knife blade is generally in the range of 5 to 6.5.

HardnessMineralCommon ar test
1TalcEasily scratched with a fingernail
2GypsumScratched by a fingernail (2.5)
3CalciteScratched by a coin (3)
4FluoriteDifficult to scratch by a nail (4); scratched conveniently by a knife (5)
5ApatiteDifficult to scrape with a knife (>5); right scratches glass (5.5)
6FeldsparScratched by a steel file (6.5); easily scratches glass
7QuartzScratches a steel document and glass
8TopazDifficult to check 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 test kit have the right to be easily produced from usual household or hardware item (table 6). Parental should assist children make the kit. Wear safety glasses and gloves as soon as cutting class. All piece in the hardness test kit must be contrasted to one another and certain minerals through a recognized hardness.

Approximate HardnessItem
1Blackboard Chalk
2.5Fingernail
3Copper penny
4Common nail
5.5-6.5Pocket knife
5.5Window glass (2 customs square; usage caution making this scratch plate. Ice the edges of the glass v duct tape. You may have the ability to get this reduced at a local hardware store.)
6.5Steel file or tempered steel. Shot to find an old, broken or worn flat file

Luster

Luster is how a mineral mirrors light. The terms metallic and nonmetallic define the straightforward types of luster. Table 7 lists the most usual terms provided to define luster and an instance of a matching mineral. Part minerals that don"t exhibit luster are described as "earthy," "chalky," or "dull."

Color

One of the most obvious properties that a mineral is color. Color should be taken into consideration when identifying a mineral, yet should never be supplied as the major identifying characteristic.

Streak

Streak is the color of the powdered mineral, which is usually much more useful for identification 보다 the shade of the whole mineral sample. Rubbing the mineral on a streak bowl will create a streak. A streak plate have the right to be make from the unglazed earlier side that a white porcelain restroom or kitchen tile. Some minerals won"t streak because they space harder 보다 the streak plate.

Specific Gravity

Specific gravity is the ratio in between the fixed (weight) the a mineral and the fixed (weight) the an equal volume the water. A mineral"s particular gravity (SG) can be figured out by separating its weight in wait by the load of an equal volume the water. Because that instance, quartz v a density of 2.65 is 2.65 time as hefty as the very same volume of water.


Cleavage

The way in which a mineral breaks along smooth level planes is referred to as cleavage. This breaks happen along airplane of weakness in the mineral"s structure. However, if a mineral breaks along an rarely often rare surface, it does not have cleavage.

Fracture

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

Tenacity

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

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

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Other Diagnostic Characteristics

Other attributes may be useful in identifying some minerals:

Transparency - Objects room visible once viewed with a mineral.Translucency - Light, but not one image, is transmitted v a mineral.Opaqueness - No irradiate is sent , also on the thinnest edges.Taste - Taste can be offered to assist identify some minerals, such together halite (salt).Acid reaction - thing reacts to hydrochloric acid. The most separating characteristic of calcite is the it effervesces when hydrochloric mountain is applied. Dolomite reflects a reaction on a freshly damaged or powdered surface. Testing for calcite, limestone, or dolomite calls because that 10% hydrochloric acid, but solid white vinegar have the right to be substituted for the acid.Magnetism - Magnetism is a separating characteristic of magnetite.Crystal form - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Part crystal shapes are shown below.

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