Ever more people need ever more materials. There are many examples of how growing demand is putting pressure on the supply of materials. As mineral deposits are depleted we are increasingly turning to harder-to-access, more expensive sources. Western society depends overwhelmingly on oil-based plastics, derived from this finite resource. Plant-based materials compete with food production. Building materials require quarrying which destroys the natural environment. And both increased logging and larger plantations degrade virgin forests.
Some resources, such as rare minerals, are non-renewable. Once they have been used up they are gone forever. Unfortunately, especially with mineral resources, conventional economics can be misleading about their abundance; more account is often taken of the human effort to extract them than of their value as non-renewable geological resources. Economists treat revenues from the depletion of natural capital as income – "growth". For instance, "increasing oil production" means "consuming even faster our dwindling stock of the most versatile and precious of our irreplaceable fossil fuels".
Many other resources are 'renewable' because they are naturally regenerated. But even these are not unlimited; we can only go on using them in the long term if we do not exceed the rate at which they are naturally regenerated. Unfortunately, it isn't always obvious when we are over-using a particular type of resource, either locally or globally.
Human ingenuity has found all sorts of ways to overcome shortfalls in one resource by using more of another. For instance, developed countries use nonrenewable energy resources (oil and natural gas) to manufacture fertilisers in order to grow a larger amount of food than would otherwise be possible using genuinely sustainable methods of agriculture. When talking about sustainability, it is always necessary to see the bigger picture.
Read more about materials.
Read more about minerals.
Read more about what things are made of.