Rocks, minerals, and the study of the Earth.
Test your knowledge with these top questions!
Which gas fizzes out when vinegar drops onto limestone?
Limestone holds carbonate that releases carbon dioxide bubbles when acid touches it.
Which California valley is famed for towering granite cliffs?
Yosemite granite started as magma that cooled underground, then glaciers stripped softer rock to expose the cliffs.
After feldspar, how abundant is quartz in Earth's continental crust?
Quartz resists weathering, so it builds up in sandstones and beach sands across continents.
Limestone blocks form most of the core of which ancient Egyptian monuments?
Giza builders quarried nearby limestone beds, hauling millions of blocks to stack the pyramid cores.
Moonstone shows a soft floating glow because it is a variety of which mineral?
Moonstone glows because light scatters between thin stacked layers inside the feldspar.
Marble consists mainly of which carbonate mineral?
Marble forms when limestone recrystallizes, so its calcite grains lock together.
Amethyst is the purple variety of which common mineral?
Trace iron plus natural radiation gives amethyst its purple color within quartz crystals.
Which Indian mausoleum is faced with white Makrana marble?
The Taj Mahal uses white Makrana marble that shifts tone through the day.
What process shapes cooling basalt into hexagonal columns like Giant's Causeway?
As thick lava cools, it shrinks and cracks into tight polygonal joints, often six-sided columns.
Many limestone beds began as the skeletons of which shallow-ocean builders?
Coral skeletons are calcium carbonate, the same mineral that compacts into limestone over time.