1.Classification by color
Like the yellow color of sulfur or the lime green color of olivine, there are many ore minerals that are able to be classified by color. Minerals change color by the reflection of light on its surface. One reason behind the difference of color is the trace elements contained in the minerals. Trace elements are elements that do not appear in the mineralfs chemical formula. Another reason behind the difference of color is the gap between atoms or ionic groups. The gaps causes the light refract in a different way causing the color of the mineral to change. Some examples of this are opal and moon stone.
2.Classification by sheen
The reflection of light on the surface of the mineral is called the sheen. The sheen of minerals can be divided into metallic lustre and nonmetallic lustre. Gold , silver ,and copper all share the characterisitcs of having metallic lustre, meaning that it is opaque. On the other hand, most minerals with nonmetallic lustre share a transparent characterisitc. Nonmetallic minerals can be divide into 8 more specific categories: vitreous lustre, adamantine lustre, resinous lustre, nacreous lustre, silky lustre, dull lustre, and submetallic lustre.
3.Classification by streak color
The streak color of an mineral is the color of the powder when it is dragged across an un-weathered surface. When classifyiing minerals, the streak color is more commonly used than the color of the mineral itself. While, the color of the mineral varies considerably, the streak color of one mineral has a more consistent characterisitc. For example, the oxide mineral of iron, hematite creates a red streak, and another type of oxide mineral of iron, magnetite crearts a black streak.
4.Classification by cleavage
The cleavage is the tendency of a mineral to break along smooth planes parallel to zones of weak bonding. The cleavage surface normally is flat and reflects light at a certain rate. There are minerals with prominent cleavage and others that show no cleavage at all.
5.Classification by fracture
There are some cases where the minerals breaks without the effect of cleavage. Scientifically, we call this fractures. Fractures are often found in metallic minerals, and quartz.
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6.Classification by tenacity
Many minerals have unique features due to its crystallis structure.
- Malleability...the mineralfs ability to deform under compressice stress.
- Machinability...the ease of cutting the mineral
- Flexibility...the ability of a mineral to deform elastically and return to its original shape when the applied stress is removed
- Ducutility...the ability of a solid mineral to deform under tensile stress, to be stretched into a wire
- Brittlenesscthe ability of a mineral to break without significant deformation.
- Elasticity...the ability of a mineral to stretch
7.Classification by solidity
The hardness of a mineral is definied by how well a mineral resists getting scratched by another substance. The harder the mineral is, the harder to get a scratch on it. The Mohs hardness scale has a scale of 1-10, ranking diamond as 10 and talc as 1. The harder the mineral is, the more brittle it becomes. Most phosphate minerals, carbonate minerals, sulphate minerals, halide minerals, sulphate minerals, and hydrothermal minerals are soft compared to anhydrous oxide minerals and silicate minerals.
‡GClassification by the refractive index
The refractive index differs for each transparent and translucent mineral. The higher the refractive index, the brighter the mineral gets. There are many ways to research the refractive index of minerals, even ones for small kids!
‡HClassifaction by fluorescence
Some minerals produce a visible, fluorescent light under ultraviolet rays. The minerals that were found around these minerals also tend to have the same characterisitcs.
