Geology PAG 1: Investigating minerals and rocks

Suggested Activity 1: Mineral testingInstructions for teachers and techniciansThis practical activity is composed of two parts; a teacher/technician section and the student activity which can be found on page 7. This practical activity supports OCR AS/A Level Geology.

When distributing the activity section to the students either as a printed copy or as a Word file you will need to remove the teacher instructions section.

This is a suggested practical activity that can be used as part of teaching the OCR AS and A Level Geology specifications helping to fulfil the requirements of the Practical Endorsement.

These are not required activities, nor are they coursework tasks.

You may modify these activities to suit your students and centre. Alternative activities are available from, for example, ESTA, Earth Learning Idea, CLEAPSS and publishing companies. Support for mapping

activities to the requirements of the Practical Endorsement is available from OCR – see www.ocr.org.uk/positiveaboutpractical or email us at PASS@ocr.org.uk.

Students can collaborate during the activities but each student must individually demonstrate competence in each of the practical skills being assessed (see Practical Skills below).

It is possible for a student to achieve some but not all of the practical skills involved in an activity (and this can be recorded as individual skills in the OCR PAG Tracker).

Further details are available in the specifications (Practical Skills Topics).

OCR recommendations:

Before carrying out any experiment or demonstration based on this guidance, it is the responsibility of teachers to ensure that they have undertaken a risk assessment in accordance with their employer’s requirements, making use of up-to-date information and taking account of their own particular circumstances. Any local rules or restrictions issued by the employer must always be followed.

CLEAPSS resources are useful for carrying out risk-assessments: (http://science.cleapss.org.uk).

Centres should trial practical activities in advance of giving them to students. Centres may choose to make adaptations to this practical activity, but should be aware that this may affect the Apparatus and Techniques covered by the student.

This activity has been adapted from a SchoolRocks! activity which accompanies their secondary school loan boxes. You can contact SchoolRocks! by email at schoolrocks@geologistsassociation.org.uk

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 1 © OCR 2018

DISCLAIMERThis resource was designed using the most up to date information from the specification at the time it was published. Specifications are updated over time, which means there may be contradictions between the resource and the specification, therefore please use the information on the latest specification at all times. If you do notice a discrepancy please contact us on the following email address: resources.feedback@ocr.org.uk

IntroductionThis is an introductory practical activity which can be adapted to suit the resources that you have available in your centre. The skills covered will be revisited later in the course in applied and fieldwork contexts. Students will investigate selected diagnostic properties of a range of silicate and non-silicate mineral samples to identify the samples using a mineral key. Students are expected to have studied modules 2.1.1, and have familiarity with laboratory procedures from their experience of GCSE (9-1) science. While students have experience of using hierarchical keys in classification from Y4 onwards, in science, they may find it difficult to apply this understanding outside common objects and will often rely on their everyday perceptions rather than fundamental diagnostic properties (taxonomic approach); in one study secondary students systematically classified penguins as amphibians rather than birds. A common misconception for geology students is to picture match rather than classify or to identify all sparkly and/or colourless minerals are quartz.

Aims to investigate and record the key diagnostic properties (e.g. hardness) of mineral samples to safely handle dilute hydrochloric acid (HCl) to test mineral samples to investigate the density of mineral samples to make recordings in an organised and scientific manner

Intended class time 1 hour

Practical Skills – competence assessed by the teacher1.2.1 (b) safely and correctly use a range of practical equipment and materials1.2.1 (c) follow written instructions1.2.1 (d) make and record observations/measurements 1.2.1 (e) keep appropriate records of experimental activities1.2.1 (f) present information and data in a scientific way1.2.1 (j) use a wide range of experimental and practical instruments, equipment and techniques appropriate to the knowledge and understanding included in the specification1.2.2 (f) application of classification systems using distinguishing characteristics to identify unknown minerals and fossils1.2.2 (j) use of appropriate apparatus to record a range of quantitative measurements (to include mass, volume)1.2.2 (k) use of physical and chemical testing to identify minerals to include1.2.2 (l) use of methods to increase accuracy of measurements, such as timing over multiple observations, or use of a fiducial scale

CPAC – competence assessed by the teacher(1) follows written procedures(2) applies investigative approaches and methods when using instruments and equipment(3) safely uses a range of practical equipment and materials(4) makes and records observations

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Links to Specifications2.1.1 (a)(i) the diagnostic physical properties of rock-forming minerals in hand specimens; to include: colour, lustre, shape, streak, cleavage/fracture, density, hardness, reaction with acid2.1.1 (a)(ii) the classification of samples, photographs and thin section diagrams of minerals using their diagnostic physical properties; to include the application of the diagnostic properties of the major rock-forming minerals2.1.1 (a)(iii) practical investigations to determine the density and hardness of mineral samples; to include Mohs hardness test, density test2.2.1 (a)(iv) the techniques and procedures used to measure mass, length and volume

Mathematical Skills – learning opportunity within activityMathematical skills must be applied in the recording of the data and calculations, and in analysing the data. These steps require the appropriate application of the following mathematical skills:o M1.1 Recognise and make use of appropriate units in calculations.o M1.3 Use an appropriate number of significant figures.o M1.4 Use ratios, fractions and percentages.o M2.2 Construct and interpret frequency tables and diagrams, bar charts and histograms

Chemicals

LabelIdentity / amount

required per learner or group

Hazard information

Hydrochloric acidHCl(aq)Solutions <2.7 M

Colourless liquid

dilute (2 mol dm-3) hydrochloric acid, HCl(aq)

c. 20 cm3

Currently not classified as hazardousWear eye protection even when dilute solutions are used.Experience of the use of this acid in school science activities indicates that it is appropriate to apply the control measures given here. It is advisable to include a warning to this effect on the label.

EquipmentEach student/pair of students will require:

Option A Option B

hand lens, ×10 magnification; Moh’s hardness testing kit, hardness pencils

or Mohs mineral set or simple substitutes such as finger nail, 2mm coper wire, wire nail and masonry nail;

streak plate, or unglazed porcelain tile such as bathroom tiles

dropper bottle with HCl (2 mol dm-3); displacement can and 100 ml measuring

cylinder with 1 cm3 graduated scale and a piece of thread

balance reading to at least two decimal places

splash-resistant goggles;

hand lens, ×10 magnification; Moh’s hardness testing kit, simple substitutes

such as finger nail, 2mm coper wire, wire nail and masonry nail;

streak plate, or unglazed porcelain tile such as bathroom tiles

dropper bottle with HCl (2 mol dm-3); displacement can and 100 ml measuring

cylinder with 1 cm3 graduated scale and a piece of threadbalance reading to at least two decimal places

splash-resistant goggles; a minimum of four unknown minerals, with at

least one carbonate mineral (see Notes)

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a minimum of four rock forming minerals with at least one carbonate mineral (see Notes)

Mineral testing resource sheet (attached)

Mineralogical Society of America Mineral Identification Key (abbreviated or online)

Health and Safety Health and safety should always be considered by a centre before undertaking any practical

work. A full risk assessment of any activity should be undertaken including checking the CLEAPSS website (http://www.cleapss.org.uk).

Hydrochloric acid/HCl(aq) is covered under CLEAPSS Hazcard number 47a. Students should wear eye protection when working with hydrochloric acid, even when dilute solutions are used.

NotesCentres are advised to trial this activity before using it with students. In particular: This activity has been adapted from a SchoolRocks! activity which accompanies their school

loan boxes. Schools can request a Rock Box containing a selection of fossils, minerals and rock that support the relevant primary or secondary curriculum from SchoolRocks! Contact SchoolRocks! by email at schoolrocks@geologistsassociation.org.uk;

Minerals should be clean and unweathered, they do not need to be museum grade. There is not a requirement to have a teaching set containing every major rock forming mineral. The availability and cost of mineral samples varies all the time and a teaching set can be supplemented with field samples and incidental acquisition. Suppliers such as Geo Supplies Ltd and UKGE Ltd will offer advice and can create sets of loose samples. Having a few more spectacular minerals or examples that will key out can be a useful learning tool. Be aware that the more luridly coloured mineral samples found in crystal shops may be dyed.

This activity may either be used as an introductory practical early in the course (Option A) or as a more advanced activity later in the course (Option B) using minerals samples that the students have collected on fieldtrips or their holidays. Where a centre uses both options it is suggested that they map the criteria from PAG 1.1 to PAG 1 Activity 4 on the Map your Centre Activities tab on the OCR activity tracker; this approach can then provide clear evidence of students’ progression in their competence against the CPAC criteria.

If there are insufficient displacement vessels then a measuring cylinder of sufficient diameter to measure the volume of individual mineral samples by displacement can be used

Option A, you will need to edit the Mineral testing resource sheet to include the minerals you will be using in the classroom. Remind students that the skill is in being able to use reference material and identification keys, it is never about memorising the reference material. A basic set for this activity could contain: silicates – quartz, orthoclase; sulphides – galena, pyrite; carbonates – calcite.

Option B, students will need access to either the abbreviated Mineralogical Society of America’s Mineral Identification Key resource or the full online Mineral Identification Key http://www.minsocam.org/msa/collectors_corner/id/mineral_id_keyi1.htm . Remind students that the skill is in being able to use reference material and identification keys – it should never be about memorising the reference material.

HCl may have a relatively short shelf life. It is advisable to test solution in the drop bottles to assess the degree of reaction and, if necessary, make up a fresh solution from stock. it may help to show students www.youtube.com/watch?v=AK_Z63UvQjE;

The streak should be tested in advance, especially if the students are using the unglazed surfaces of kitchen/bathroom tiles.

Answers and Guidance to Extension Activities9. See the Geology Drawing Skills Handbook for guidance on scientific drawings, As a guide drawings

should have a title and scale, be recognisable and in proportion and have appropriate

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annotation. Drawing the setup of apparatus has been introduced in all reformed A Level sciences and similar straight forward tasks have proved problematic for students of Biology, Chemistry and Physics in written assessments. It is worth practising this skill with students and getting them to peer assess example drawings; try asking the question, if I follow the illustration will the technique work; e.g. is a sharp edge being used for the Mohs test, is the displacement can filled up to the edge of the drip funnel?

10. For Option A students should be able to identify all the minerals although it is likely that colour will be much less useful than the other characteristics. Minor contamination or the substitution of one ion for another in the mineral structure; for example a 100 ppm substitution of Fe for Si in quartz causes the purple colour of amethyst. Students will have produced classification keys in science from KS2. For example

For Option B students are more likely to key out and may need to check their observations and then work through the key again. For some minerals there are hundreds of minor variants and being able to identify amphibole or pyroxene from using a key is sufficient.

11. Systematic errors in the measuring cylinder and balance which could be identified by a calibration (for example weigh 10 × £1 coins = 87.50 g). Measuring cylinder is an analogue instrument with an instrument error of ±½ of one scale division = ±0.5 cm3 (= ±1.0 cm3 if using the differencing method). The balance is a digital instrument and the instrument error will be quoted in the instruction booklet (e.g. ±0.01 g). Random errors may be caused by the student, others will be environmental (e.g. precise point over flow starts and stops). The example:

systematic error mass of 10 × £1 coins = 87.72 gzero error = 87.50 – 88.72 = –0.22 g

volume of quartz sample 4.5 ±0.5 cm3

mass of quartz sample 11.00 – 0.22 = 10.78 ±0.01 gmaximum density 10.79 ÷ 4.0 = 2.2 g cm-3

minimum density 10.77 ÷ 5.0 = 2.7 g cm-3

measured density of quartz 2.4 ±0.3 g cm-3

percentage error (0.3 ÷ 2.4) × 100 = 12.5%

RecordsAs evidence for the Practical Endorsement, students: should not need to re-draft their work, but rather keep all of their notes as a continuing record

of their practical work, dating their work clearly, should record any measurements taken to the number of significant figures (resolution)

appropriate. This should be recorded clearly in a table format with appropriate units, should record any modifications to supplied procedures, including their own risk assessments

and methods where appropriate

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Extension questions help students develop their understanding of the underlying geological theory and are a preparation for the written examinations. They also help students develop the practical science skills assessed indirectly in the written examinations and they should be encouraged to record their data appropriately, for example showing full workings in calculations, and stating final answers to the appropriate number of significant figures.

Document updatesv1 February 2018 Original version.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 6 © OCR 2018

OCR Resources: the small printThis formative assessment resource has been produced as part of our free A Level teaching and learning support package. All the A Level teaching and learning resources, including delivery guides, topic exploration packs, lesson elements and more are available on the qualification webpages.

If you are looking for examination practice materials, you can find Sample Assessment Materials (SAMs) on the qualification webpages: http://www.ocr.org.uk/qualifications/as-a-level-gce-geology-h014-h414-from-2017/ OCR’s resources are provided to support the teaching of OCR qualifications, but in no way constitute an endorsed teaching method that is required by the Board, and the decision to use them lies with the individual teacher. Whilst every effort is made to ensure the accuracy of the content, OCR cannot be held responsible for any errors or omissions within these resources.

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Geology PAG 1: Investigating minerals and rocks

Suggested Activity 1: Mineral testing – Option A

Student activityIntroductionIn this practical activity you will be investigating selected diagnostic properties of a range of silicate and non-silicate mineral samples and applying your results to classify the samples using reference material. There are hundreds of naturally occurring minerals however by applying the skills developed in this practical you will be able use a standard identification key to identify most of them.

The skills covered will be revisited later in the course in applied and fieldwork contexts. You are expected to have studied module 2.1.1 and have a basic understanding of rock forming minerals.

Aims to investigate and record the key diagnostic properties (e.g. hardness) of mineral samplesto safely handle dilute hydrochloric acid (HCl) to test mineral samplesto investigate the density of mineral samplesto make recordings in an organised and scientific manner

Intended class time1 hour

Equipmenthand lensMohs hardness testing kitstreak platedisplacement canmeasuring cylinderbalancethreaddropper bottle with HCl (2 mol dm-3)splash-resistant gogglesaccess to four unknown mineral samples

Health and Safety Hydrochloric acid/HCl(aq) is covered under CLEAPSS Hazcard number 47a. You should wear

eye protection when working with hydrochloric acid, even when dilute solutions are used Handling rocks should not introduce any additional risk to the class environment. You should

follow your centre’s practice on handling environmental and geological materials.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 7 © OCR 2018

ProcedureBefore starting your practical work, read the information below.

1. Decide how you will organise your practical work. It is not essential that you carry out the tasks in the order given. Ensure that you record all of your results in a suitable format.

2. Record the overall colour of each mineral. Be as accurate as possible, for example dark bluey grey rather than just grey.

3. Record the lustre of each mineral. Hold it in direct light and decide which adjective best describes the appearance of the unweathered mineral: metallic, adamantine (diamond), vitreous (glassy), earthy (dull), pearly, or waxy (resinous).

4. Record the streak colour of each mineral. Select a clean, unweathered point on the specimen:a. Put the streak plate flat on the laboratory bench;b. Hold the plate firmly and pull the point of the specimen across the streak plate;c. Examine the streak. Make sure that a powder has been produced.

5. Record the relative hardness of minerals using the Mohs scale of hardness:a. Select an unscratched surface to test and hold the sample firmly against the bench.b. Starting with the softest reference mineral drag it firmly across the mineral facec. Use the hand lens to check whether there is a line left by the test mineral or a scratch

on the mineral being tested; d. The Mohs scale goes up in ½ units so interpolate the hardness between the test

minerals that is just softer and the test mineral that scratches it6. Record how vigorously the mineral reacts with a few drops of dilute HCl.7. Calculate the density of the mineral sample and record the value in your results table :

a. Measure the mass of the sample to a resolution of 0.01 g;b. Lower the sample by the thread into the displacement jar and measure the volume of

the sample. You should interpolate between the 1 ml graduations on the measuring cylinder to a resolution of 0.5 cm3;

c. Divide mass by volume to calculate the density of the sample in g cm-3.8. Compare the values in your results table with the reference table and identify each mineral.

Extension opportunities9. Draw the equipment set up for carrying out the Mohs hardness and Density tests. You should

show each piece of equipment and add annotations explaining the procedure to use.10. Could you identify all the minerals? Construct a simple branching key that will allow you to

classify the unknown minerals in three to four questions. Which mineral properties were most useful for identifying minerals, and which were more ambiguous and less useful?

11. Evaluate the sources of error in the density test. These will include instrument errors (measuring cylinder and balance) and may also include errors caused by the method used. Which of these are random errors and which are systematic? Assign values to each error and calculate the percentage error in the calculated mineral density values.

RecordsAs evidence for the Practical Endorsement, you need records of:

your mineral tests results table including the classification you have given each sample; processing of raw data to calculate mineral density equipment set up drawing and notes for either the density test or the Mohs hardness test

All work should be clearly dated.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 8 © OCR 2018

In addition you should have considered the above questions as the answers to these questions will aid you in preparation for your written examinations.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 9 © OCR 2018

Geology PAG 1: Investigating minerals and rocks

Suggested Activity 1: Mineral testing – Option B

Student activityIntroductionIn this practical activity you will be investigating selected diagnostic properties of a range of silicate and non-silicate mineral samples and applying your results to classify the samples using reference material. There are hundreds of naturally occurring minerals however by applying the skills developed in this practical including the use of a standard identification key you will be able to identify most of them.

The skills covered will be revisited later in the course in applied and fieldwork contexts. You are expected to have studied module 2.1.1 and a basic understanding of rock forming minerals.

Aims to investigate and record the key diagnostic properties (e.g. hardness) of mineral samplesto safely handle dilute hydrochloric acid (HCl) to test mineral samplesto investigate the density of mineral samplesto make recordings in an organised and scientific manner

Intended class time1 hour

Equipmenthand lensMohs hardness testing kitstreak platedisplacement canmeasuring cylinderbalancethreaddropper bottle with HCl (2 mol dm-3)splash-resistant gogglesunknown mineral samplesMineralogical Society of America, Mineral Identification Key, abbreviated or the full version which is available online at www.minsocam.org/msa/collectors_corner/id/mineral_id_keyi1.htm

Health and Safety Hydrochloric acid/HCl(aq) is covered under CLEAPSS Hazcard number 47a. You should wear

eye protection when working with hydrochloric acid, even when dilute solutions are use Handling rocks should not introduce any additional risk to the class environment. You should

follow your centre’s practice on handling environmental and geological materials

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 10 © OCR 2018

ProcedureBefore starting your practical work, read the information below.

1. Decide how you will organise your practical work. It is not essential that you carry out the tasks in the order given. Ensure that you record all of your results in a suitable format.

2. Record the lustre of each mineral. Hold it in direct light and decide which adjective best describes the appearance of the unweathered mineral: metallic, adamantine (diamond), vitreous (glassy), earthy (dull), pearly, or waxy (resinous).

3. Record the relative hardness of minerals using the Mohs scale of hardness:a. Select an unscratched surface to test and hold the sample firmly against the bench.b. Starting with the softest reference mineral drag it firmly across the mineral facec. Use the hand lens to check whether there is a line left by the test mineral or a scratch

on the mineral being tested; d. The Mohs scale goes up in ½ units so interpolate the hardness between the test

minerals that is just softer and the test mineral that scratches it4. Record the streak colour of each mineral. Select a clean, unweathered point on the specimen:

a. Put the streak plate flat on the laboratory bench;b. Hold the plate firmly and pull the point of the specimen across the streak plate;c. Examine the streak. Make sure that a powder has been produced.

5. Record the overall colour of each mineral. Be as accurate as possible, e.g. dark bluey grey.6. Record how vigorously the mineral reacts with a few drops of dilute HCl.7. Calculate the density of the mineral sample and record the value in your results table :

a. Measure the mass of the sample to a resolution of 0.01 g;b. Lower the sample by the thread into the displacement jar and measure the volume of

the sample. You should interpolate between the 1 ml graduations on the measuring cylinder to a resolution of 0.5 cm3;

c. Divide mass by volume to calculate the density of the sample in g cm-3.8. Identify each mineral using the Mineral Identification Key.

Extension opportunities9. Draw the equipment set up for carrying out the Mohs hardness and Density tests. You should

show each piece of equipment in clear diagrammatic form and add annotations explaining the procedure to carry out the test.

10. Could you identify all the minerals? What did you do if the mineral keyed out – reached the end of the key without being identified? Which mineral properties were most useful for identifing the mineral and which properties were more ambiguous and less useful?

11. Evaluate the sources of error in the density test. These will include instrument errors (measuring cylinder and balance) and may also include errors caused by the method used. Which of these are random errors and which are systematic? Assign values to each error and calculate the percentage error in the calculated density valuesl.

RecordsAs evidence for the Practical Endorsement, you need records of:

your mineral tests results table including the classification you have given each sample; processing of raw data to calculate mineral density equipment set up drawing and notes for either the density test or the Mohs hardness test

All work should be clearly dated.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 11 © OCR 2018

In addition you should have considered the above questions as the answers to these questions will aid you in preparation for your written examinations.

This document may have been modified – if in doubt check the master version on OCR Interchange.Version 1 – February 2018 12 © OCR 2018

Resource SheetMohs hardness scale

Mohs Scale Hardness Test Mineral Substitutes

1 Talc

2 Gypsum 2½ fingernail

3 Calcite 3½ copper

4 Fluorite 4½ wire nail

5 Apatite 5½ masonry nail/streak plate

6 Feldspar 6½ streak plate

7 Quartz

8 Topaz

9 Corundum

10 Diamond

Some minerals may be harder in one direction and softer in another. For example mica is twice as hard across the thin edges of the crystals compared to the wider flat faces of the crystal.

Mineral testing resource sheet

Resource SheetRock forming minerals – examples

HardnessMohs scale Colour Streak Lustre Acid Test Density

g cm3 Mineral

2 colourless, white or grey white

vitreous, pearly or

earthyno reaction 2.3 gypsum

2–2½ white to pale gree/yellow white vitreous no reaction 2.8–2.9 muscovite

2½ grey-black to black

bluish-black to grey metalic no reaction 7.6 galena

3 colourless, tan, white, or grey white

vitreous, pearly or

waxy

reacts vigorously 2.7 calcite

3½–4 white to tan or pinky grey white vitreous or

pearlyreacts slowly 2.85 dolomite

3½–4 colourless, white, or grey white vitreous to

waxyreacts

vigorously 2.95 aragonite

4

colourless, green, purple, blue, yellow,

pink

white vitreous no reaction 3.2 fluorite

5–6 greenish-black or dark-green white vitreous no reaction 3.0–3.5 amphibole

5–6medium-green, light-yellow to pale-bronze

white vitreous or earthy no reaction 3.2–3.6 pyroxene

6–6½ white to salmon pink white vitreous no reaction 2.5–2.6 orthoclase

6–6½ white to dark grey white vitreous no reaction 2.6–2.8 plagioclase

6½–7pale-yellow to olive-green to

dark brownwhite vitreous to

sub-metallic no reaction 3.3–4.4 olivine

6–6½ brass-yellow black metalic no reaction 5.0 pyrite

7

colourless, rose to purple, smoky-grey to brown-yellow

– vitreous no reaction 2.65 quartz (crystal)

7

milky, grey to Black, red, to brown-yellow, green, blue,

–vitreous to

waxy to earthy

no reaction 2.65 quartz (massive)

Mineral testing resource sheet