Minerals
Minerals are naturally occurring crystalline solids.
About this topic
Minerals are naturally occurring, inorganic, solid substances with a definite chemical composition and ordered crystal structure. Rocks are made of minerals: granite contains quartz, feldspar and mica. Minerals are identified by colour, streak, hardness (Mohs scale from talc 1 to diamond 10), lustre, cleavage and density.
Some are valuable ores like haematite (iron), bauxite (aluminium) and galena (lead); others are gems or used in construction and electronics. Quartz is the most common mineral at the surface.
Look at a piece of granite and you can often see three minerals: glassy grey quartz, pink or white feldspar that cleaves in flat faces, and shiny black flakes of mica. Hardness tests are practical: a fingernail scratches talc and gypsum (about 2), a copper coin scratches minerals up to about 3, a steel knife up to about 5.5, and quartz scratches glass. A streak test, rubbing the mineral on unglazed porcelain, shows the true powder colour, which can differ from the surface, such as haematite that is silver but leaves a red-brown streak.
Crystal shape reflects atoms packing in an ordered way, giving cubes in halite (table salt) or six-sided prisms in quartz. Minerals underpin technology: silicon from quartz is used in chips, copper conducts electricity, and graphite and diamond show how the same element (carbon) can form very different minerals through different structures. A common misconception is that a mineral and a rock are the same; a rock is a mixture of minerals, though some such as limestone are mostly one. Also, coal is not a mineral because it comes from organic matter.
Key ideas
- Hardness on the Mohs scale
- Streak and cleavage
- Quartz and feldspar are common
Quick check
Use cases: where Minerals helps
- Homework: review the key idea behind Minerals before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Minerals without notes.
- Visual learning: play with the interactive lab to see how Minerals changes when you adjust its inputs.
- Teaching a friend: explain Minerals in your own words, then compare your version with the key ideas.
Earth science helps with weather forecasts, natural hazards, energy and climate planning.
Frequently asked questions
What is Minerals?
Minerals are naturally occurring crystalline solids.
What will I learn in Minerals?
Hardness on the Mohs scale. Streak and cleavage. Quartz and feldspar are common.
Is Minerals part of Earth & Space?
Yes. It is one of 60 Earth & Space topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Minerals lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Minerals?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.