Physical properties of minerals

Physical properties of minerals such as luster, cleavage, color, streak, hardness, fracture, transparency, magnetism, and tenacity.

1. Physical Properties of Minerals Prepared by: Jerome A. Bigael , Leyte Progressive High School

2. To classify a mineral resource, the minerals in the rock should first be identified. Minerals can be identified through their physical properties. In some cases, some minerals may be found in different places and in different forms but their fundamental physical properties remain the same.

3. 1.Color The most evident characteristic of and is usually the first property used to identify minerals. It is a result of the way minerals absorb light. When a mineral absorbs all the color of spectrum except that of a certain color , the mineral will appear in that color

4. However, this property may not be used in identifying translucent to transparent minerals due to the presence of other trace minerals or impurities.

5. Mineral Mineral Color Augite Brown, green ,black ,purple Biotite Black, brown, green Calcite Pearlescent and pale colors Dolomite Colorless , pink, pale brown Feldspar Yellow, white, pink, green, gray Hematite Metallic gray or black Hornblende Green, yellow, brown, black Limonite Black, brown, yellow Sulphur Pale gold

6. Augite = Brown , green ,black ,purple

7. Biotite = Black , brown, green

8. Calcite = Pearlescent and pale colors

9. Dolomite = Colorless , pink, pale brown

10. Feldspar = Yellow, white, pink, green, gray

11. Hematite = Metallic gray or black

12. Hornblende = Green, yellow, brown, black

13. Limonite = Black, brown, yellow

14. Sulphur = Pale gold

15. 2.Streak The color of mineral in powder form. Usually the mineral is rubbed on a streak plate to determine its color .

16. 3.Hardness The measure of the mineral’s resistance to scratching. To quantify the hardness of a mineral, the Mohs Scale is used. The harder the mineral, the less prone to scratches.

17. Mohs Relative Hardness Mineral Common Objects 1 Talc powder 2 Gypsum fingernails 3 Calcite tooth 4 Fluorite Iron nail 5 Apatite Window glass 6 Feldspar Steel file 7 Quartz porcelain 8 Topaz Hardened steel 9 Corundum Sapphire and ruby 10 Diamond none

18. 4.Cleavage and Fracture Cleavage and fracture are used to describe how minerals break into pieces.

19. 5.Crystalline structure/crystal lattice The periodic array of atoms This is a unique arrangement of atoms in a crystal. A hand lens is used for checking the crystalline structure. Non crystalline structure minerals are called “ amorphous ”; special lenses are needed to validate this.

20. 6.Transparency/Diaphaneity Indicate the extent of light that can pass through the mineral. The degree of transparency may depend on the thickness of mineral.

21. 7.Magnetism Indicates the ability of the mineral to attract or repel other materials.

22. 8.Tenacity the mineral’s ability to hold its particles together or the mineral’s level of resistance to stress such as bending, breaking, crushing, or tearing . It indicate if the material is brittle, elastic, malleable, etc.

23. 9.Luster Shows how much light is reflected in a mineral. This depends on the brilliance of light used to observe the surface of the mineral.

24. Classifications of Luster : Metallic, mineral is opaque and behaves like metal when reflecting light. Submetallic, mineral is opaque, dull, and dark colored . Nonmetallic , mineral does not reflect light like a metal. Waxy, mineral looks like paraffin. Vitreous, mineral looks like a broken glass.

25. 10.Odor The distinct smell of a mineral that is usually released from a chemical reaction manifested when the mineral is subjected to water, heat, air and friction. Sulfur , for example smells like what is emitted when lighting a match. The strength of this smell increases when heated or stuck, giving off an odor similar to rotten eggs.

26. 11.Specific Gravity It is the measure of the density of the mineral. It determines how heavy the mineral is by its weight to water. Specific gravity is used especially when two minerals have the same size and color .

27. Other Properties: Taste – some minerals have a characteristic taste. For example Halite tastes like salt.

28. Acid Reaction Some minerals that contain carbonate (CO 3 ) will react with diluted hydrochloric acid ( HCl ), forming carbon dioxide(CO 2 ) gas bubbles. Calcite (CaCO 3 ) will react with HCl

29. Feel Some minerals such as talc, feel soapy or greasy.

30. Presence of Striations Some minerals, such as pyrite, have closely spaced fine grooves on their crystal faces.  the state of being marked with stripes or lines.