Most minerals have the right to be characterized and classified by their distinctive physical properties: hardness, luster, color, streak, certain gravity, cleavage, fracture, and also tenacity.
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The capability to withstand being scratched—or hardness—is one of the most beneficial properties for identifying minerals. Hardness is established by the capacity of one mineral to scrape another. Federick Mohs, a German mineralogist, created a hardness range (table 5) making use of a set of ten standard minerals. The scale arranges the minerals in order of boosting hardness. Each higher-numbered (harder) mineral will scratch any kind of mineral through a lower number (softer).
A unstable measure that mineral hardness can be made 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 tiny harder than 3, window glass arrays from 5.5 to approximately 6 in hardness, and also a knife tongue is typically in the selection of 5 to 6.5.
|Hardness||Mineral||Common ar test|
|1||Talc||Easily scratched with a fingernail|
|2||Gypsum||Scratched by a fingernail (2.5)|
|3||Calcite||Scratched by a penny (3)|
|4||Fluorite||Difficult to scratch by a pond (4); scratched easily by a knife (5)|
|5||Apatite||Difficult to scrape with a knife (>5); barely scratches glass (5.5)|
|6||Feldspar||Scratched through a steel file (6.5); conveniently scratches glass|
|7||Quartz||Scratches a steel file and glass|
|8||Topaz||Difficult to test in the field|
|9||Corundum||Difficult to check in the field|
|10||Diamond||Difficult to test in the field|
Creating a Mineral Hardness test Kit
|5.5||Window glass (2 inch square; usage caution making this scrape plate. Ice the edge of the glass v duct tape. You may be able to get this reduced at a neighborhood hardware store.)|
|6.5||Steel record or tempered steel. Shot to discover an old, broken or worn flat file|
Luster is just how a mineral mirrors light. The state metallic and also nonmetallic define the simple types of luster. Table 7 perform the most typical terms offered to define luster and an example of a matching mineral. Part minerals that don"t exhibition luster are described as "earthy," "chalky," or "dull."
One of the most obvious properties that a mineral is color. Shade should be taken into consideration when identify a mineral, but should never be offered as the significant identifying characteristic.
Streak is the shade of the powdered mineral, i beg your pardon is usually an ext useful because that identification 보다 the shade of the entirety mineral sample. Rubbing the mineral on a streak key will produce a streak. A streak plate deserve to be do from the unglazed ago side the a white porcelain restroom or kitchen tile. Part minerals won"t streak because they room harder than the streak plate.
Specific gravity is the ratio in between the mass (weight) of a mineral and the mass (weight) that an equal volume that water. A mineral"s specific gravity (SG) have the right to be determined by dividing its load in wait by the load of an equal volume of water. For instance, quartz with a density of 2.65 is 2.65 times as hefty as the same volume the water.
The means in i m sorry a mineral breaks follow me smooth flat planes is called cleavage. This breaks occur along plane of weakness in the mineral"s structure. However, if a mineral breaks along an rarely often rare surface, the does not have cleavage.
When a mineral division irregularly, the breaks are called fractures. The breaks deserve to be defined as grainy, hackly (jagged), conchoidal (curved), or splintery.
How fine a mineral resists wrong is well-known as tenacity. Tenacity is defined using this terms:Brittle - Mineral crushes come angular pieces (quartz).Malleable - Mineral deserve to be modification in form without breaking and can be planarization to a thin sheet (copper, gold).Sectile - Mineral have the right to be cut with a knife right into thin shavings (talc).Flexible - Mineral bends however doesn"t gain back 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 characteristics may be valuable in identifying some minerals:Transparency - Objects space visible once viewed v a mineral.Translucency - Light, but not one image, istransfer through a mineral.Opaqueness - No light is transmitted, even on the thinnest edges.Taste - Taste have the right to be provided to help identify part minerals, such together halite (salt).Acid reaction - object reacts come hydrochloric acid. The most distinguishing characteristic that calcite is that it effervesces when hydrochloric mountain is applied. Dolomite reflects a reaction on a freshly broken or powdered surface. Experimentation for calcite, limestone, or dolomite calls because that 10% hydrochloric acid, but strong white vinegar have the right to be substituted because that the acid.Magnetism - Magnetism is a distinguishing characteristic of magnetite.Crystal shape - Cubic, rhombohedral (tilted cube), hexagonal (six-sided), etc. Part crystal forms are portrayed below.