00:00 Rocks and minerals make up our planet and many objects in the universe, and this episode explores what they are and the differences between them.

02:18 A rock is an aggregation of minerals, and a mineral is a naturally occurring solid with a well-defined chemical composition and crystal structure, with ice being an example of a mineral that can have different crystalline structures.

04:30 Minerals with the same chemical composition can be different due to the different pressures and temperatures at which they were created, resulting in different crystalline structures, and common minerals like Feldspar can have different combinations of elements.

06:26 Opal is an amorphous gemstone that doesn't have a crystalline structure, and the most common minerals inside the earth are usually never or seldom found on the surface, such as perovskite which makes up a large percentage of the earth's volume.

08:24 Extrusive igneous rocks make it to the surface and are almost uniformly black with small grain size, while sedimentary rocks form when rock is eroded and broken down into smaller particles, and limestone forms when calcium carbonate precipitates out of the water, and metamorphic rock is created when pre-existing rock is changed due to pressure and temperature.

10:27 Metamorphic rocks are formed through increased heat and pressure, and can provide information about the conditions in which the rock was formed, while the rock cycle involves the recycling and renewal of rocks through processes such as erosion, rising magma, and the formation of igneous rock.

12:19 Minerals can be incredibly beautiful, and some of the best collections can be found at the Smithsonian Museum of Natural History, the Australian Museum, the Museum of Natural History in New York, the Natural History Museum in London, and the Royal Ontario Museum, but the Houston Museum of Natural Science may have the greatest collection in the world.