Name: ______________________ Earth Science Date _______ Period: _____ Lab 9: Elements / Minerals Objective: What is the relationship between elements and minerals? Introduction: Below is a pie chart of the most abundant elements in the Earth’s crust. You will use the data from the pie chart to create a table below. List the elements from the MOST abundant to the least. Then answer the questions. Element Symbol Percentage by Mass in Earth’s Crust Answer all Questions in complete sentences (except # 1 and 6) 1. Where can you find a similar table to your on the ESRT? ___________________________ 2. The first eight elements listed in your table together make up what percentage of the Earth’s crust? ______________________________________________________________________ ______________________________________________________________________ 3. Which element is the most abundant? _________________________________________ 4. Which element is the second most abundant? ____________________________________ 5. Together oxygen and silicon make up what percentage of the Earth’s crust? _____________ 6. There are only 92 naturally occurring elements in the Earth’s crust; however there are over 2,500 minerals. Explain how this can be possible. _________________________________ ______________________________________________________________________ 7. The elements gold, silver and platinum are called precious metals. One meaning of precious is “of great value or high price.” Why do you think these metals are so highly valued? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 1 Part II: Silicate Minerals Many from a Few P1 The Earths’ crust is made up of many different elements. However a random sampling of soil would contain mainly the elements oxygen and silicon. Most of the remaining portion of the sample would contain the metallic elements aluminum, iron, calcium, sodium, magnesium, and potassium. The minerals formed from a combination of oxygen, silicone and some metals are members of the family called silicates. P2 Elements combine to form over 2,500 different types of minerals. About 92% of these minerals are made in part from oxygen and silicon atoms. If most minerals are made up of these 2 atoms, you might expect all minerals to look alike. However, two common silicates, quartz and mica do not look alike at all. P3 Another group of silicate minerals—the feldspar group—has two main divisions: potassium feldspar (orthoclase) which breaks at right angles when it fractures, and plagioclase, which breaks at angel less than 90o. How can there be so many varieties of minerals if there are only 2 major building blocks? The answer lies in the way the atoms are arranged. Different metallic atoms (K, Ca, or Na) substitute for each other in the atomic structure. The variation in the properties of the feldspar group depends on which of the metals is most abundant in the atomic structure. P4 The smallest unit of a mineral, or molecule, found in silicate minerals contains 1 silicon and 4 oxygen atoms. These 5 atoms form the basis of the silica tetrahedron (see below). In the simplest case, a silicon atom links tetrahedrons together to form a single chain. Metal atoms can also serve as the link between single-chain tetrahedrons. In addition, silica tetrahedron can either form double chains or appear in sheets. Quartz is made entirely of tightly bonded tetrahedra. Feldspar is made of single chains joined mostly by Aluminum. 2 Mica is formed from a sheet-like grouping of tetrahedrons. The different way of arranging these few element form the variety of minerals found all over the Earth. 1. What are silicate minerals? ___________________________________________________________________ ___________________________________________________________________ 2. How are the atoms arranged in a silica tetrahedron? ____________________________ ___________________________________________________________________ 3. Why don’t silicate minerals all look alike? ____________________________________ ___________________________________________________________________ __________________________________________________________________ 3 Elements & Minerals: ESRT Practice 1. Name the two elements that are most abundant in the Earth’s crust: _________________ 2. Elements are found in (equal/unequal) amounts in the Earths’ crust. (circle one) 3. Which of the minerals listed in the ESRT are silicates? 1) _________________________ 6) ________________________ 2) _________________________ 7) ________________________ 3) _________________________ 8) ________________________ 4) _________________________ 9) ________________________ 5) _________________________ 10) ______________________ 4. Which element is found in all three layers: the crust, hydrosphere and the troposphere? _____________________________________________________________ 5. Minerals are made from elements. Predict which two elements are found in most minerals. 6. Minerals are found in (equal / unequal) amounts in the Earth’s crust. (Circle one). Explain: ________________________________________________________________ ______________________________________________________________________ 7. Mixtures of minerals are called ______________________. 8. From ESRT page 6, Scheme for Igneous Rock identification, determine and list the names of the minerals found in Granite. 1) _________________________ 4) ________________________ 2) _________________________ 5) ________________________ 3) _________________________ 9. List the all the minerals that could be found in Basalt. 1) _________________________ 3) _________________________ 2) _________________________ 4) _________________________ 5) ________________________ 4 .