Minerals

1. Minerals Chapter 3

2. Minerals must occur naturally. Cannot be man made. Cement, bricks, steel, and glass all come from materials found in the earth, but these are made by people. Naturally Occurring

3. Inorganic materials were never living. Coal is made from the remains of ancient plants and animals, so coal is not a mineral. Inorganic

4. Naturally occurring Inorganic solid Crystal structure Definite chemical composition Minerals

5. The state of matter when the material is below its freezing point. Definite shape, definite volume. Particles are fixed in place. Solid

6. The particles of the material line up in a regular, repeating pattern. Has flat sides called faces, that meet at sharp edges and corners. Crystal Structure

7. Always contains certain elements in the same proportion. Almost all minerals are compounds, which are two or more different elements bonded together (holding hands). Pyrite is two sulfur atoms holding hands with an atom of iron. Definite Chemical Composition

8. Have a definite format. Written together means they are bonded. Coefficients tell how many of the whole thing you have. Subscripts tell how many of the atom before it that you have. So 2H means two separate hydrogen atoms. H2 mean two hydrogen atoms holding hands. H2O means two hydrogen atoms holding hands with an oxygen atom. Chemical Formula’s

9. 2 H2O means you have two separate water molecules, each containing two hydrogen and one oxygen atom. Bornite is a copper ore that turns purple when exposed to air. It’s formula is Cu5FeS4. So how many of each atom are present? Five copper one iron four sulfur More Formula’s

10. Each mineral has specific properties that can be used to identify it. Hardness density luster color streak crystal system cleavage and fracture special properties Identifying Minerals

11. A measure of how easily a mineral can be scratched. Determined by the atomic structure of the mineral. Friedrich Mohs developed the scale we use today. Hardness

12. Minerals will have a certain density regardless of the size of the sample. When geologists compare the weight of the mineral to the weight of an equal volume of water it is called specific gravity. Density

13. Not especially useful in identifying minerals, as some minerals like quartz can come in a variety of colors. Color

14. The way a mineral reflects light. Can be metallic or non-metallic. Shiny or dull. Earthy, waxy, pearly, glassy. Luster

15. The color of its powder. Not always the same as the color of the mineral. Pyrite has a gold color, but its streak is a greenish black. Streak

16. Gemstones • Gemstonesare highly valued for their beauty and rarity, than for their usefulness. • Important gemstones include diamond, sapphire, ruby, emerald, aquamarine, topaz, and tourmaline.

17. Rocks Chapter 4

18. A solid made of one or more minerals and other materials. Rocks are:

19. Classifying Rocks • Rocks are classified based on how they were formed.

20. Rocks are further identified by: color texture mineral composition Identifying Rocks

21. Chapter 4 Section 1The Rock Cycle Types of Rock Click below to watch the Visual Concept. Visual Concept

22. Texture • Textureis the quality of a rock that is based on the sizes, shapes, and positions of the rock’s grains.

23. Composition • Compositionis the chemical makeup of a rock. Composition can describe either the minerals or other materials in the rock.

24. Particles of minerals that make up a rock. Texture is determined by grain size, grain shape, and grain pattern. Grains

25. Some rocks have grains that are large and easy to see. These rocks are coarse grained. Other rocks have grains so small they are microscopic. These are fine grained rocks. Grain Size

26. Grains can be: fine sand crystals fragments that can be smooth or jagged Grain Shape

27. Grains can lie flat in layers like a stack of pancakes. Some have patterns that look like waves or swirls Some resemble rows of beads. Others will have random patterns. Grain Pattern

28. Some rocks resemble pieces of glass. These rocks cooled very quickly so crystals did not have time to grow. No Visible Grain

29. Since rocks are really combinations of minerals, geologists must slice their samples into very thin pieces to test which minerals are present. Mineral Composition

30. Rocks are classified by the way they are formed. Igneous rocks: formed from the cooling of molten rock. Sedimentary rocks: formed from sediments being compacted and cemented. Metamorphic rocks: existing rock that is changed by heat, pressure, or chemicalreactions. Origin of Rocks

31. Identified by origin, texture, and mineral composition. From the Latin word “ignis,” which means fire. Tend to have average densities. Igneous Rocks

32. Extrusive rock is formed from lava that erupted on the surface and rapidly cooled. Will have tiny crystals, be very fine grained, and sometimes even appear glassy. Basalt is most common of this type. Extrusive Igneous Rock

33. Basalt Forming

34. Forms when magma cools underground. Usually cools slowly, so it will have large crystals and be coarse grained. Granite is most common intrusive rock. Intrusive Igneous Rock

35. Lava at the surface cools quickly, so crystals do not have time to grow. Rock is a good insulator, so rock cooling underground takes much longer. So intrusive rock will have larger crystals. Large Crystals

36. How would you explain an intrusive rock that had both large and small crystals? Right! It must have cooled slowly at first, then cooled more rapidly as it got closer to the surface. Explain This!

37. These rocks look like Jell-O with fruit mixed in. Deep underground the heat cannot dissipate as rapidly, so the rock cools slowly. Near the surface the heat can escape into the air, so it cools rapidly. Porphyritic Rock

38. Lighter colored igneous rocks will have lots of silica. They tend to be less dense than the darker versions. Felsic Igneous Rock

39. Less silica means these rocks will be darker than their felsic counterpart. They will be denser also. Mafic Igneous Rock

40. Little silica →→→→→→→→→→→→ lots of silica

41. Sill • Slab of volcanic rock that squeezes between rock layers. • Tend to be horizontal.

42. Dike • Slab of volcanic rock that cuts across rock layers. • Tend to be vertical.

43. Batholith • A very large mass of volcanic rock that form deep underground. • Can cover several states in the USA. • Stone Mountain might be part of an exposed batholith.

44. Stock • Smaller area of volcanic rock than a batholith • Stone Mountain might be a stock that is exposed.

46. Formed from particles of sediment deposited by wind and water. Sediment is small pieces of solid materials that come from rocks or living things. Sedimentary Rocks

47. Wind, water, ice, sunlight, and gravity all cause rock to physically weather into fragments. Through erosion, these rock and mineral fragments, calledsediment,are moved from one place to another. The sediment is deposited in layers, and eventually newer layers cover the older layers. Origins of Sedimentary Rock

48. Chapter 4 Section3 Sedimentary Rock Sedimentary Rock Cycle Click below to watch the Visual Concept. Visual Concept

49. What do these rocks have in common? Question?

50. Yes, all these rocks are layered or “stratified.” Stratification