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

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Hardness

The capability to stand up to being scratched—or hardness—is among the most helpful properties for identifying minerals. Hardness is identified by the ability of one mineral to scratch another. Federick Mohs, a German mineralogist, developed a hardness range (table 5) using a set of ten conventional minerals. The scale arranges the mineral in stimulate of increasing hardness. Each higher-numbered (harder) mineral will scratch any mineral with a reduced number (softer).

A stormy measure of mineral hardness have the right to be made by assembling a kit of comfortable objects (table 6). A fingernail has actually a hardness varying from 2 come 2.5, a penny is a small harder than 3, window glass ranges from 5.5 to roughly 6 in hardness, and a knife tongue is normally in the selection of 5 come 6.5.

HardnessMineralCommon field test
1TalcEasily scratched with a fingernail
2GypsumScratched through a fingernail (2.5)
3CalciteScratched by a penny (3)
4FluoriteDifficult to scrape by a nail (4); scratched conveniently by a knife (5)
5ApatiteDifficult to scrape with a knife (>5); barely scratches glass (5.5)
6FeldsparScratched by a steel record (6.5); quickly scratches glass
7QuartzScratches a steel record 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 can be easily created from typical household or hardware items (table 6). Parents should assist children do the kit. Wear security glasses and gloves once cutting class. All pieces in the hardness test kit need to be compared to one an additional and particular minerals through a well-known hardness.

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

Luster

Luster is just how a mineral shows light. The state metallic and nonmetallic define the simple types the luster. Table 7 perform the most common terms provided to define luster and an instance of a matching mineral. Some minerals that don"t exhibition luster are referred to as "earthy," "chalky," or "dull."

Color

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

Streak

Streak is the color of the powdered mineral, i m sorry is usually more useful for identification than the shade of the entirety mineral sample. Rubbing the mineral on a streak plate will develop a streak. A streak plate deserve to be made from the unglazed back side that a white porcelain toilet or kitchen tile. Part minerals won"t streak since they are harder 보다 the streak plate.

Specific Gravity

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


Cleavage

The method in which a mineral breaks follow me smooth level planes is called cleavage. These breaks occur along plane of weak in the mineral"s structure. However, if a mineral breaks along an rarely often, rarely surface, it does not have cleavage.

Fracture

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

Tenacity

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

Brittle - Mineral crushes to angular fragments (quartz).Malleable - Mineral deserve to be amendment in form without breaking and can be flattened to a slim sheet (copper, gold).Sectile - Mineral deserve to be reduced with a knife into thin shavings (talc).Flexible - Mineral bends but doesn"t restore 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 qualities may be advantageous in identifying some minerals:

Transparency - Objects are visible as soon as viewed v a mineral.Translucency - Light, yet not one image, is sent through a mineral.Opaqueness - No light is sent , also on the thinnest edges.Taste - Taste can be offered to aid identify some minerals, such as halite (salt).Acid reaction - thing reacts to hydrochloric acid. The most separating characteristic that calcite is the it effervesces once hydrochloric acid is applied. Dolomite shows a reaction ~ above a freshly broken or powdered surface. Trial and error for calcite, limestone, or dolomite calls because that 10% hydrochloric acid, but solid white vinegar deserve to be substituted for the acid.Magnetism - Magnetism is a separating characteristic that magnetite.Crystal shape - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Some crystal forms are illustrated below.

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