What is the hardest natural substance on Earth?

Which famous gemstone weighs 45.52 carats and is said to carry a curse?

What temperature (in degrees Celsius) does quartz crystalize?

Which mineral is known as 'fool's gold'?

In what year was the largest diamond ever found, the Cullinan Diamond, discovered?

Which rock type forms from cooling magma or lava?

What percentage of Earth's crust is composed of oxygen?

Which mineral leaves a distinctive red-brown streak when scratched on porcelain?

What is the primary mineral component of limestone?

At what depth (in km) does the Earth's crust transition to the mantle?

Which gemstone is composed of hydrated silica?

What is the Mohs hardness of pure gold?

Which metamorphic rock forms from limestone under intense heat and pressure?

What percentage of the world's diamonds are gem quality?

Which mineral is essential for making Portland cement?

What is the most abundant mineral in Earth's crust?

At what temperature (in °C) does diamond turn to graphite?

Which famous ruby weighs 167.97 carats and belongs to the British Crown Jewels?

What percentage of Earth's mantle is composed of olivine?

Which mineral can split into extremely thin, flexible sheets?