Earth and Environmental Science 11–12 · Year 11
Panning for gold: separating a dense mineral from sand by density
Module 1: Earth’s Resources
The idea
Alluvial gold is recovered because it is far denser than quartz sand (gold up to about twenty times the density of water, quartz sand 2.7, Earthlearningidea), so washing sorts the grains, the principle behind panning, jigs and sluices.
What you need
- gold pan, or a shallow pan such as a frying pan (Earthlearningidea)
- 500 g of washed medium-grained sand mixed with 2.00 g of stand-in ‘gold’: brass filings with no jagged edges, or pyrite crushed and sieved to 2 mm or less (Earthlearningidea)
- large tub half full of water, small jug, kitchen sieve, paper towel
- balance to 0.01 g for the grade and recovery calculations
How to do it
- Weigh 500 g of sand and 2.00 g of brass filings or crushed pyrite, mix them and calculate the grade in grams per tonne.
- Scoop the mixture into the pan with plenty of water; swirl or jiggle the pan so the water carries the sand back into the tub over the lip.
- Keep adding water and panning until only the dense grains and a little heavy sand remain.
- Dry the recovered grains on paper towel, weigh them and calculate recovery (%) = mass recovered / mass added × 100; repeat three times and compare techniques.
- Relate the result to the density contrast and to Geoscience Australia’s account of the science of gold.
What you should see
Recovery rises with practice as the learner finds a technique that washes the sand out while the denser grains stay in the pan. Pyrite, at a relative density of 5.0 (webmineral gives 5 to 5.02; Earthlearningidea's figure of about 6 is too high), is much denser than quartz sand at 2.7 but much less dense than gold, so real gold separates even more cleanly. The seeded grade is 2.00 g of stand-in in 502 g of mixture, which is 3980 g per tonne of mixture (4000 g per tonne of sand alone); ore grades are quoted per tonne of ore, so the learner can compare the model with a published mine grade once the basis is stated.
What changes
- What you change
- panning technique
- What you measure
- recovery (%) by mass
- What you keep the same
- same sand mass and seeded mass
- same grain size of the stand-in
- same water depth
- same operator per trial
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Gold is found because it is shiny.
- Bigger grains are always denser.
Safety card
Hazards
- wet floor
- sharp edges on brass filings or pyrite fragments
Controls
- work outdoors or over the tub
- use filings with no jagged edges (Earthlearningidea)
- the teacher crushes the pyrite in advance wearing safety glasses
- wash hands
Note
No hazardous chemicals or heat sources: record the activity in the school's RiskAssess risk assessment, following the NSW Department of Education Science safety and compliance page; the Chemical Safety in Schools package is not triggered.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-8EES11/12-3EES11/12-4EES11/12-5
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-11-02
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.
- www.nsw.gov.au/education-and-training/nesa/curriculum/science/earth-and-environmental-science-stage-6-2017
- www.earthlearningidea.com/PDF/164_Gold_panning.pdf
- www.earthlearningidea.com/PDF/133_Jigging.pdf
- www.ga.gov.au/education/classroom-resources/the-science-of-gold-teacher-notes-and-student-activities
- www.webmineral.com/data/Pyrite.shtml