Materials, Minerals and Finite Resources
Australia exported $124 billion of iron ore in 2023, but Rio Tinto's Pilbara mines have only about 20 years of reserves left at current extraction rates.
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Q1 · Think about your phone, laptop, or a car, where do you think the metals and minerals inside them originally come from, and how might they be extracted?
Q2 · If a key mineral used in phone batteries became very rare and expensive, what do you think would happen to technology and society?
● Know
- Where materials come from (minerals, ores, living organisms)
- How Aboriginal and Torres Strait Islander Peoples used minerals and resources for many purposes
- Why most materials are finite resources
- The stages of a material's lifecycle
● Understand
- Why recycling alone cannot solve resource depletion
- How lifecycle assessment gives a complete environmental picture
- Why reducing and reusing are preferred over recycling
● Can do
- Apply the waste hierarchy to material decisions
- Evaluate a sustainability claim using lifecycle evidence
- Identify trade-offs in material extraction and use
If you drive through Newman, Western Australia, you can watch hundred-metre-wide open pits being blasted open to reach haematite rock that is roughly 60% iron, it looks like rust-red rubble, yet this ore feeds every steel mill on Earth. Most metals are found in the Earth's crust combined with other elements as ores mineral compounds from which the metal can be extracted economically. Iron ore (haematite, Fe₂O₃) is crushed, then heated with coke in a blast furnace (smelting) to produce pig iron. Aluminium is extracted from bauxite ore using the Bayer process and then the Hall-Héroult electrolysis process. These extraction processes require enormous amounts of energy, smelting one tonne of aluminium uses about 15,000 kWh of electricity.
Materials are classified as renewable (can be regrown or regenerated on human timescales, timber, wool, cotton) or non-renewable (formed over millions of years and cannot be replaced, iron ore, coal, bauxite). Once a mineral ore deposit is mined out, it is gone forever. This scarcity drives recycling: it takes 95% less energy to recycle aluminium than to smelt it from ore, which is why aluminium recycling is economically valuable.
The Pilbara region of Western Australia contains the world's largest known iron ore deposits, over 50 billion tonnes of haematite. Rio Tinto and BHP operate 15 separate mine sites there, exporting about 900 million tonnes of ore per year, mostly to steel mills in China.
Australia is the world's largest exporter of iron ore, lithium, and bauxite. The NSW government manages mining licences under the Mining Act 1992, every mine site requires an environmental impact statement before ore extraction begins, because mining permanently alters the landscape.
The materials-science thinking in this unit, choosing a material because of its physical properties, is not new. Aboriginal and Torres Strait Islander Peoples have selected and used minerals, rocks and other natural resources for tens of thousands of years, matching each material to a job because of its hardness, colour, workability or chemistry. These knowledges were developed and passed down over many generations, and they continue today.
Ochre is a clay or rock rich in iron oxides, the same iron compounds found in haematite ore. Ground into a fine powder and mixed with water or animal fat, ochre provides red, yellow, brown and white pigments used for rock art, body decoration and ceremony. Ochre was also used on skin as a sunscreen and insect repellent and in some medicines. High-quality ochre was valued so much that it was traded along routes stretching hundreds of kilometres across the continent.
Stone was selected for very different properties. Hard, tough stones such as greenstone and basalt were ground and shaped into axe heads, and flat stones were used as grinding stones to grind native seeds into flour, some of the earliest evidence of bread-making in the world. Stones that fracture to a sharp edge, such as silcrete, quartz and chert, were flaked into knives, spear points and scrapers. Clays were shaped and fired into vessels and used to line ovens for cooking.
Choosing greenstone for an axe because it is hard and tough, but chert for a blade because it flakes sharp, is exactly the property-to-purpose matching a materials engineer does today. It shows a deep, tested understanding of how materials behave, built up and refined over an immense span of time.
At Wilgie Mia in Western Australia, ochre has been mined by Aboriginal people for more than 30,000 years, making it one of the oldest continuously used mines on Earth. The bright red ochre from this site was traded across large parts of the continent, showing both deep materials knowledge and far-reaching trade networks.
- Ochre
- Greenstone
- Chert
- Flakes to a sharp edge for cutting tools
- Iron-oxide rich, ground into coloured pigment
- Hard and tough, shaped into axe heads
A lifecycle assessment (LCA) tracks the total environmental impact of a material or product from extraction of raw materials, through manufacturing, transport, use, and finally disposal or recycling. The LCA asks: how much energy, water, and land does each stage consume? What pollutants are released? The full picture is often surprising, a cotton T-shirt uses about 2,700 litres of water to produce, far more than a polyester shirt, even though polyester comes from non-renewable petroleum.
LCA findings change engineering decisions. When companies discovered that manufacturing a lithium-ion battery releases more CO₂ than operating a petrol car for 2–3 years, they invested in renewable-powered battery factories. LCA also guides recycling priorities: aluminium has very high LCA benefit from recycling (95% energy saving); glass recycling saves only about 30% energy because melting glass is unavoidable. LCA makes environmental costs visible the first step to reducing them.
LCA of a steel bridge beam: iron ore mining (CO₂, land disturbance) → blast furnace smelting (large CO₂) → transport to fabricator → welding and coating (VOC emissions) → 50 years of use → demolition → 90% recycled as scrap steel. The recycling stage offsets roughly 40% of the total lifecycle emissions.
CSIRO's LCA research team in Canberra provides lifecycle data for Australian industries. Their work showed that Australian residential construction using lightweight steel framing has a 15% lower lifecycle carbon footprint than equivalent timber framing when accounting for harvesting, processing, and transport distances across the continent.
NSW manages waste using the waste hierarchy, a priority order for how society should deal with materials: (1) Avoid generating waste in the first place, (2) Reduce the amount used, (3) Reuse the item, (4) Recycle the material, (5) Recover energy, and (6) Dispose to landfill as a last resort. Each step down the hierarchy represents a greater loss of the material's embodied energy and value.
NSW has implemented several programs that apply the hierarchy to specific materials. The Return and Earn container deposit scheme (launched 2017) pays 10 cents per eligible container returned, a financial incentive that has recovered over 10 billion containers from landfill. The NSW single-use plastic bag ban reduced checkout bag use by over 80% in the first year. Industrial recycling programs target construction waste, in NSW, 70% of construction and demolition material is now diverted from landfill and recycled.
A 600 mL PET water bottle recycled via Return and Earn: consumer returns bottle (10c refund) → bale of PET flake collected → melted and extruded into polyester fibre → woven into a recycled polyester T-shirt. The recycled PET uses 70% less energy than making virgin PET from petroleum.
NSW's Return and Earn scheme has the highest container recovery rate in Australia, over 80% of eligible containers are returned. Revenue from the 10c deposits funds community programs across NSW, and the recovered material feeds directly back into Australian packaging manufacturers.
According to the waste hierarchy, the best option is to generating waste in the first place. The next steps are to the amount used, then reuse the item. After reuse comes , where the material itself is reprocessed. Disposal to is the last resort, representing the greatest loss of value. NSW's Return and Earn scheme pays per container, applying the hierarchy in practice.
At the start of this lesson, you heard that Australia exports $124 billion worth of iron ore per year, more than any other country, and that every tonne of steel on Earth came from ore dug out of the ground. But minerals are finite, and that raises a serious question about the future of the materials we depend on.
Now that you've worked through the lesson, how has your thinking shifted? Can you explain the difference between renewable and non-renewable resources, and suggest what might happen to steel production if iron ore deposits are exhausted without alternatives?
Q1. Explain the difference between a finite and a renewable resource. Give one example of each used in everyday products.
Q2. Using the waste hierarchy, evaluate three possible responses to the problem of old smartphone disposal. Rank them from most to least preferred and justify your ranking.
Q3. A company claims their product is 'environmentally friendly' because it uses recycled plastic. Evaluate this claim using lifecycle assessment thinking.
Model answers (click to reveal)
SAQ 1 (2 marks)
Model answer: A finite resource is one that exists in a limited amount and cannot be replaced once it is used up, because it took millions of years to form. A renewable resource can be regrown or replaced naturally within a human timescale, so it does not run out if it is managed carefully. For example, iron ore used to make the steel in a car body is a finite resource, while timber used to make wooden furniture is a renewable resource because trees can be replanted.
SAQ 2 (3 marks)
Model answer: Three responses to old smartphone disposal are: reusing the phone by passing it on to another user, recycling it to recover valuable metals, and throwing it into landfill. Ranked from most to least preferred: (1) reuse, (2) recycle, (3) dispose to landfill. This order follows the waste hierarchy, which ranks avoiding and reusing above recycling, and recycling above disposal. Reuse is best because it keeps the whole phone and all its embodied energy in service, so no new materials need to be extracted. Recycling is next best because it recovers finite metals such as gold, lithium, and copper for new products and uses far less energy than mining fresh ore, although some material is still lost in processing. Disposal to landfill is the worst option because the valuable finite resources are lost forever and toxic components can leak into the environment.
SAQ 3 (3 marks)
Model answer: Using recycled plastic does reduce the environmental impact of the raw material stage, because it avoids extracting new petroleum and uses less energy than making virgin plastic. However, a lifecycle assessment looks at every stage from raw material extraction through manufacturing, transport, use, and final disposal, not just one stage. The product could still have a high overall impact if its manufacturing uses a lot of energy, if it is transported long distances, or if it cannot be recycled again and ends up in landfill. Therefore the claim that the product is 'environmentally friendly' is only partly justified. To fairly evaluate it, you would need lifecycle data for all stages, so the claim should be treated with caution until the full lifecycle impact is known.