Describing Rocks and Minerals

Transcription

1 Science Unit: Lessn 1: Gelgy and Plate Tectnics Describing Rcks and Minerals Schl Year: 2011/2012 Develped fr: Develped by: Grade level: Duratin f lessn: Laura Secrd Elementary Schl, Vancuver Schl District Linda (Hansn) Herbert (scientist); Lesley Chambers and Phil Green (teachers) Presented t grade 6/7; apprpriate fr grades 3 7 with age apprpriate mdificatins 1 hur and 20 minutes Ntes: Reasnably priced rck kits can be purchased frm Fisher Scientific. These 50 piece kits cntain numbered samples f a variety f minerals, rcks f all three types, res f cmmn metals and samples fr cnducting hardness tests. Item: Classrm cllectin, catalgue # S84011 If streak plates are unavailable yu can use the unglazed back f a regular prcelain tile. Many hardware stres will give yu their brken tiles fr free, just ask. The surface used fr the streak tests shuld be white r light in clr. Objectives 1. Learn the difference between rcks and minerals. 2. Observe a variety f rck and mineral samples. 3. Practice making and recrding scientific bservatins. Backgrund Infrmatin All rcks are made f minerals. Minerals are hmgeneus materials that ccur naturally in the earth s crust. Sme rcks are pieces f a single type f mineral while thers are cmpsed f multiple minerals. The minerals fund in a particular rck sample will ften allw it t be identified. Gelgists use specific physical prperties t help them identify the minerals fund in rcks. Sme f the mre cmmn prperties include clur, streak, luster, hardness, crystal structure, cleavage, magnetism, transparency and specific gravity. The prperties we will be examining in this lessn are defined belw. Vcabulary Minerals: Rcks: Luster: Streak: Cleavage: Magnetism: Gelgist: Pure, naturally ccurring inrganic elements r chemical cmpunds. Have a welldefined chemical cmpsitin. The building blcks f rcks. Made up f ne r mre minerals. Describes the shine f a rck/mineral sample. The mark left behind when a rck r mineral is rubbed acrss a rugh surface like a streak plate. The way in which certain minerals fracture alng distinct planes. This results frm the chemical structure f the mineral s crystals. A characteristic that describes if a mineral is attracted t ther magnetic substances (such as a magnet). A scientist wh studies rcks and minerals. Gelgy and Plate Tectnics_Lessn 1 1

2 Materials Rck kits (1 per grup) magnifying glasses (if available) magnets (1 per grup) handuts f the Mhs hardness scale (1 per grup streak plates (minimum f ne per grup) r unglazed prcelain tiles with white backs paper clips (r nails) and cpper pennies (pre 1982) fr hardness tests if desired In the Classrm Intrductry Discussin 1. Hld up a large rck sample such as granite ask students what is this? and wait fr the answer, a rck. Hld up a very different lking rck sample (such as bsidian) and again ask what is this? Ask the students why they think rcks cme in s many different types. Recrd discussin ideas n the bard and/r have students recrd in their science ntebks. Questins t help guide the discussin as it evlves: Hw d rcks differ frm ne anther? What is a mineral? What is a rck? What are sme prperties that we can use t describe and classify rcks? Recrd student ideas n the bard. Describe the varius prperties as they are mentined and intrduce related vcabulary wrds (mineral, rck, luster, crystal, cleavage etc.). Ask: What prperties d gelgists use t describe and classify rcks? Clr, streak, luster, hardness, crystal structure (and size). Cleavage, magnetism, reactin with specific chemicals (recrd ideas n bard). Discuss the usefulness and limitatins f the varius prperties and hw we can bserve/test each f the prperties. Fr example: why is clr nt always a reliable prperty? Use quartz as an example t demnstrate that the clr f sme minerals can vary dramatically. This is mst cmmn in translucent minerals such as quartz where trace substances can greatly influence clr. Hw can we test hardness? Intrduce the Mhs hardness scale. Handut wrksheets and Mhs hardness scales and g ver activity instructins. 2. Shrt descriptin f ther items t discuss r review. Discuss hw scientific pictures can differ frm regular pictures in bth appearance and purpse. Scientific pictures/bservatins need t be detailed, clear and be precise. Instruct students that they shuld bserve bth rck and mineral samples. If necessary reiterate hw rcks and minerals differ t help them with this prcess. If yu have rck kits with numbered samples yu can assign specific samples t bserve r a specific range f samples they must select frm. 3. Briefly describe science experiment/activity. Students will wrk individually t bserve and recrd their bservatins f several rck/mineral specimens f their chice. 4. Briefly describe the prcesses f science that the students will fcus n: Students will fcus n making and recrding bservatins. 5. Briefly describe safety guidelines. Gelgy and Plate Tectnics_Lessn 1 2

3 D nt tuch yur face r muth while handling the rck specimens. Wash yur hands with sap at the cnclusin f the experiment and especially befre eating. Sme rck samples are high in lead r ther ptentially txic metals s washing hands at the cnclusin f the experiment is imprtant. Be careful when perfrming scratch r streak tests. If students are using pieces f tile as streak plates remind them t be careful f the brken edges as they may be sharp. Science Activity Activity Title: Describing Rcks and Minerals Purpse f Activity: T describe a variety f rcks and minerals fcusing n prperties that differ between samples and culd be used fr identificatin. Methds and Instructins: Set-up prir t experiment: Rck and mineral kits can be purchased frm Fisher Scientific r anther educatinal supplier. Brief descriptin f hw students will wrk in grups r pairs: Students will wrk in grups f 4-6 (depending n class size and the number f rck kits available). Students will recrd their bservatins individually n wrksheets. 1. G thrugh the wrksheet as a class and give the students a chance t brainstrm and cmplete each sectin as apprpriate. 2. See detailed instructins n attached wrksheet. 3. Demnstrate hw t d a streak test prir t starting the Streak Test sectin. Yu shuld d a few examples t demnstrate why streak tests are a useful tl. Fr example, ask the class t predict the clr f streak made by the pyrite sample (the sample is gld but the streak is grey). Discuss hw prspectrs used streak tests t determine if they had fund gld (gld streak) r fls gld (grey streak). Have the class predict the streak clr f rse quartz, bsidian r serpentine (all are clred but prduce a clrless/white streak). 4. Prir t starting the Gelgical Observatin sectin have students set up their Mhs hardness scale using the handut prvided. Each grup will set up ne scale. Demnstrate hw t use a systematic apprach t test the hardness f a sample using the scale. Have the students select the limestne sample (#29) Pint ut that a nail has a harness f 5 n the Mhs scale. Have the students try t scratch the limestne using the nail/paperclip. It will scratch the rck. Ask the students if this means that the rck is harder r sfter than the nail (sfter). Have them cnclude that the hardness f limestne is less than 5. Next have them try t scratch the limestne with flurite (hardness f 4 n the Mhs scale). Cntinue in a systematic fashin until they reach a sample that des nt scratch limestne (likely calcite). Have the students cnclude that that the hardness f limestne is between 3-4. Yu can have them recrd it as 3-4 r 3.5 t simplify matters. Repeat the demnstratin using a rck sample that has a hardness greater than 5 (Eg. agate, sample #47 with a hardness f ~7) 5. The rck kits used fr this lessn were purchased frm Fisher Scientific (# S84011; ~$45 each). Gelgy and Plate Tectnics_Lessn 1 3

4 Clsure Discussin 1. Discuss the results f the streak tests. Was the streak clr always what yu expected? Were there any surprises? 2. Discuss the hardness tests. Hw wuld yu figure ut the hardness f yur fingernail? 3. Why d yu think there are s many different types f rcks and minerals? Why aren t they all the same? What types f bservatins did yu recrd? What was yur mst interesting bservatin? References 1. Zim, Herbert and Paul Shaffer Rcks and Minerals: A Guide t Familiar Minerals, Gems, Ores and Rcks. Glden Press. 2. Chapman, Anita, David Barnum, Carmen Dawkins and William Shaw BC Science Prbe 7. Nelsn. 3. < Rcksandminerals4u. [website with extensive rck and mineral infrmatin, lessn plans, pht galleries and fun activities such as crsswrd puzzles.] Accessed January 10, Extensin f Lessn Plan 1. Each student shuld g hme and find a rck sample t bring in fr lessn 2 n rck families. Gelgy and Plate Tectnics_Lessn 1 4

5 DESCRIBING ROCKS AND MINERALS Scientist: Date: What wrds can we use t describe different types f lustre? Streak Tests Pick three samples t streak test. Sample # Sample clur Streak clur Explain yur bservatins; is the streak clur always the same as the sample clur? Testing fr Hardness Set up yur Mhs Hardness Scale using the handut prvided. The scientist will demnstrate hw t use the scale t test the hardness f yur samples. 1

6 Gelgical Observatin: Pick tw samples t bserve in detail. Remember t make yur scientific drawing clear and accurate. Recrd the sample s identificatin number: What clur r clurs is it? What des it lk like: Des it have layers? Visible crystals? What kind f lustre des it have? Des it have a pattern? What clur is its streak? Use the hardness scale t test hw hard it is and recrd the hardness number: What ther interesting prperties can yu bserve? Draw a detailed picture f yur sample in the bx belw. 2

7 Recrd the sample s identificatin number: What clur r clurs is it? What des it lk like: Des it have layers? Visible crystals? What kind f lustre des it have? Des it have a pattern? What clur is its streak? Use the hardness scale t test hw hard it is and recrd the hardness number: What ther interesting prperties can yu bserve? Draw a detailed picture f yur sample in the bx belw. 3