Precious Gems & Minerals
1 / 15What is the hardest natural substance on Earth?
About Precious Gems & Minerals
Test your knowledge of precious stones and minerals! This free general knowledge activity is built for older adults who want clear, readable browser-based games without sign-up friction.
General knowledge games mix recall, reasoning, and pattern recognition to keep each round varied and mentally engaging. This quiz includes 15 questions, so it works well as a quick session or as part of a longer brain-training routine. A printable version is available if you prefer offline play or want to share the game at home, in a classroom, or in a group setting.
About Precious Gems & Minerals
Give your memory a workout with Precious Gems & Minerals: 15 multiple-choice questions with a mix of 5 easy, 5 medium, 5 hard questions, free to play right in your browser. Test your knowledge of precious stones and minerals! Expect to spend about 7 minutes; every question comes with an explanation, so you learn something even when you miss.
A few sample questions
1. What is the hardest natural substance on Earth?
Answer: Diamond
Diamond is the hardest natural substance, scoring 10 on the Mohs hardness scale. It is made of pure carbon atoms arranged in a crystal structure.
2. What gemstone is traditionally associated with the month of July?
Answer: Ruby
The ruby is the birthstone for July. Rubies are a variety of the mineral corundum and get their red color from the element chromium.
3. What color is an emerald?
Answer: Green
Emeralds are green gemstones, a variety of the mineral beryl. Their green color comes from trace amounts of chromium and sometimes vanadium.
4. Pearls are primarily produced by which creature?
Answer: Oyster
Pearls are produced by oysters and some other mollusks. When an irritant enters the shell, the animal coats it with layers of nacre (mother-of-pearl), gradually forming a pearl.
5. Which precious stone is known as the 'king of gems'?
Answer: Ruby
The ruby has been called the 'king of gems' throughout history. In ancient India, rubies were called 'ratnaraj,' which translates to 'king of precious stones.'
Things you'll learn along the way
- Ruby is a variety of the mineral corundum (aluminum oxide). Sapphire is also a variety of corundum — the only difference is the trace elements that give them their colors.
- Opals are famous for their play of color, caused by the diffraction of light through tiny silica spheres within the stone. Australian opals account for about 95% of the world's supply.
- Amethyst's purple color comes from iron impurities within the quartz crystal, combined with irradiation. Amethyst is a variety of quartz and was once considered as valuable as diamonds.
Frequently asked questions
Will I lose my progress if I close the page?
Your overall progress — XP, streaks, and badges — is saved in your browser automatically. A quiz that's underway restarts if you leave mid-game, but at about 7 minutes, Precious Gems & Minerals fits comfortably in one sitting.
How many questions are in Precious Gems & Minerals?
Precious Gems & Minerals has 15 multiple-choice questions. Each one has four answer options and an explanation that appears after you answer, so you learn something even when you miss.
Is Precious Gems & Minerals free to play?
Yes. The entire SeniorBrainGames catalog — including Precious Gems & Minerals — is free, with no sign-up required, no time limits, and no ads on top of the game. It also works offline once the page has loaded once.
How long does Precious Gems & Minerals take?
Most players finish Precious Gems & Minerals in about 7 minutes. You can pause between questions, replay it as often as you like, and there is no penalty for taking your time — answers are explained after you submit them.
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