Minerals

1. Minerals

2. ESSENTIAL QUESTIONS: • What are minerals made of? • How are minerals formed? • How does the elemental composition change the properties of minerals?

3. A naturally occurring, inorganic solid with a definite chemical composition and crystal structure.

4. Definition ATTACK! What does it mean? What is confusing?

5. Minerals are… • Inorganic • The building blocks of rocks. • Found in the earth and are naturally occurring substances. They are found in dirt, rocks, and water. They are not made by man. • Usually solid crystals • About 2,000 minerals have been found. • Some minerals are rare and expensive. They are called gems.

6. Atom • Smallest unit of an element.

7. Element • An element is a substance that is made entirely from one type of atom. • It cannot be broken down into any simpler substances by chemical methods.

8. Compound • A substance that results when the atoms of two or more elements are chemically combined.

9. Inorganic • Not made of living organisms or the remains of living organisms.

10. Crystallization • This is a process in which crystals are formed. It has to do with solvents and heating them and then cooling them - when they are cooled they will form crystals.

11. Mineral Formation • Almost all minerals form from magma, the molten rock beneath the earth’s surface. • When magma cools, mineral crystals are formed.

12. When magma cools slowly, large crystals form.

13. When magma cools rapidly, small crystals form.

14. When magma cools very, very quickly on the earth’s surface, no crystals will form.

15. Mineral Formation Evaporation • Some minerals form from solutions evaporating. Elements and compounds that had been dissolved now crystallize and are visible.

16. Mineral Formation THE PRESSURE PROCESS • When a rock is subjected to high temperature and pressure, the minerals can begin to break down chemically. • The temperature and pressure becomes great enough to change the minerals in a solid state, without melting them. • The free atoms, ions, and molecules recombine in new ways, forming new minerals. More growth occurs in directions away from the pressure.

17. Atoms, elements, compounds • Minerals have an orderly arrangement of atoms. • Minerals have a definite chemical composition – they are each unique.

18. More than 90 % of the minerals in Earth’s crust are compounds containing oxygen and silicon, the two most abundant elements. • Most minerals are compounds; a few are composed of a single element.

19. Elements and Mineral properties • Minerals containing radioactive elements are radioactive • Minerals containing metals are usually very dense • Minerals containing silica (from magma) are usually very light colored • Colors of minerals are determined by the elements they are made of

20. Diamond vs. coal & graphite • Coal, Graphite, and Diamond are all made out of the element Carbon. • Why are they all different?

21. Diamond vs. coal & graphite • Heat and pressure change coal into a diamond.

22. Diamond vs. coal & graphite It is the change in crystal structure that results in the color change. Graphite is composed of flat sheets of carbon. Diamond is a 7-carbon crystal, which is 3-dimentional.

23. Diamond vs. coal & graphite • Color is a result of light absorption or light reflection. • Black means that all possible colors are being absorbed. • White means that all colors are reflected. In the case of diamond, it is clear because light passes through it.

24. Mineral Categories • Native elements – naturally occurring elements; pure and uncombined. They form the rocks of the earth’s crust. • Silicates – compounds containing silicon and oxygen. • Nonsilicates – compounds without the silicon and oxygen combination.

25. Essential question: • How can minerals be tested to determine certain physical properties needed for classification?

26. Physical Property • Characteristic that is observable in a substance without changing the chemical composition of the substance.

27. color • Sulfur- yellow • Pyrite- fool’s gold • Azurite- blue • Malachite- green

28. color • NOT reliable: • Different minerals can have the same color • Some minerals have different colors. • Minerals can change color over time through weathering.

29. streak • The powder left behind when a mineral is rubbed on an unglazed ceramic tile.

30. Why might it useful to use both black and white tiles?

31. Texture • You can feel the mineral, but often times that is not always reliable since it may have been altered by weathering or manufacturing. • A better judge of texture is grain size: Fine-grained, medium-grained, coarse- grained.

32. Density • Ratio of the mass of a substance to its volume, expressed as g/cm³.

33. Density • Use a scale to find the mass of a mineral sample in grams. • Use the displacement method we practiced before to find the volume of the mineral. • The volume of solids is reported as cc or cm3

34. Luster • Light reflected from the surface of a mineral.

35. Examples of Luster • Vitreous • Resinous • Earthy • Metallic • Pearly • Dull • Fibrous • Adamantine • Waxy

36. What is the luster of this mineral?

37. What is the luster of this mineral?

38. What is the luster of this mineral?

39. What is the luster of this mineral?

40. Hardness • Measure of the ability of a mineral to resist scratching.

41. hardness • The hardness of a mineral also depends on the arrangement of atoms, or molecules and the strength of the chemical bonds between them.

42. Moh’s Scale of Hardness • Standard against which the hardness of a mineral is tested.

43. Moh’s Scale of hardness • Talc-easily scratched with fingernail • Gypsum-scratched with fingernail • Calcite-scratched with copper penny • Fluorite-scratched with steel nail • Apatite-easily scratched with steel nail • Feldspar-scratches glass with force • Quartz-scratches glass with moderate force • Topaz-scratches glass with minimal force • Corundum-scratches glass easily • Diamond-cuts glass

44. Cleavage • Splitting of a mineral along smooth, flat surfaces. • Some minerals tend to split evenly along certain flat surfaces.

45. Cleavage • One directional • Peels off in layers • Example- biotite and muscovite.

46. cleavage • Two directional • Flat and shiny plains • Example: feldspar

47. cleavage • 3 directional • Calcite and halite • 4 directional (x,y,z, and diagonal) • fluorite

48. Fracture The uneven splitting of a mineral.

49. Crystal Structures Crystals of each mineral grow atom by atom to form a particular crystal structure.

50. If space is not restricted, a mineral will exhibit a crystal pattern with a definite number of sides and specific angles.