Rocks and Gems Quiz: Diamonds, Crystals and Gold
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Rocks and Gems Quiz: Diamonds, Crystals and Gold
About this quiz
Rocks and gems quiz: 25 questions about diamonds, crystals, gold, volcanic rocks and fossils. 💎
Rocks that float, gems hidden inside plain stones, the biggest diamond ever found and a diamond that can burn: dig into the treasures of the Earth. Great for family quiz nights, road trips and classrooms.
❓ IN THIS QUIZ
- Which rock can float on water?
- What is inside a geode?
- Where was the biggest gem diamond ever found?
- Can a diamond burn?
💬 How many did you get right? Tell us your score in the comments. Do you collect rocks or crystals?
How to play
- Read the question and look at the pictures.
- Pick your answer before the timer runs out (or switch the timer off).
- See if you were right and read the fun fact.
Answers and fun facts (spoilers!)
- Let's look at rocks and gems! Diamonds are made of which element?
Carbon
Diamonds are pure carbon, squeezed under huge heat and pressure deep underground! - Marble forms when which rock is squeezed and heated?
Limestone
Heat and pressure turn limestone into shiny marble! - What is the softest mineral on the hardness scale?
Talc
Talc is so soft you can scratch it with your fingernail! - What does the Mohs scale measure?
Hardness
It goes from 1, talc, to 10, diamond. - Which gem is red?
Ruby
Rubies get their red color from a tiny bit of chromium! - Rubies and sapphires are both made of which mineral?
Corundum
Red corundum is ruby; most other colors are called sapphire! - Which gem is famously green?
Emerald
Emeralds have been treasured since ancient Egypt! - Amethyst is a purple type of which mineral?
Quartz
Amethyst is quartz colored purple by traces of iron! - Where do pearls come from?
Oysters
An oyster coats a tiny bit of grit with layers of shiny nacre! - What is amber?
Fossil tree resin
Amber is ancient tree resin, and it sometimes traps insects for millions of years! - Which shiny black rock is natural volcanic glass?
Obsidian
Obsidian edges can be sharper than steel blades! - Which rock can float on water?
Pumice
Pumice is full of gas bubbles from volcanic eruptions! - How do most fossils form?
Minerals replace bone
Over millions of years, minerals slowly replace bones and shells, turning them to stone! - What is inside a geode?
Crystals
Geodes look like plain rocks outside, but they're full of crystals inside! - Where was the biggest gem diamond ever found?
South Africa
The Cullinan Diamond, found in 1905, weighed 3,106 carats! - Gold is so soft that you can hammer it into what?
Super-thin sheets
Gold leaf can be thinner than a human hair is wide! - Which mineral group makes up most of Earth's crust?
Feldspar
Feldspars make up about 60% of Earth's crust! - Which mineral helps many watches keep time?
Quartz
A tiny quartz crystal vibrates 32,768 times a second in a quartz watch! - What is pencil 'lead' actually made of?
Graphite
Pencil 'lead' is graphite, a soft form of carbon, just like diamond! - Table salt comes from which mineral?
Halite
Halite crystals naturally grow as perfect little cubes! - In a cave, which rock formations hang from the ceiling?
Stalactites
Tip: stalaCtites hold tight to the Ceiling; stalaGmites grow from the Ground! - White chalk cliffs are made from the remains of what?
Tiny sea creatures
Chalk is made from billions of tiny skeletons of ancient sea plankton! - Which country produces most of the world's precious opals?
Australia
Australia produces most of the world's precious opal! - How do diamonds get from deep underground to the surface?
Volcanic eruptions
Ancient volcanic eruptions carried diamonds up from deep in the mantle! - Final question! Can a diamond burn?
Yes, it's carbon
Heat a diamond hot enough in air and it burns, just like other carbon!