In a crystal, the atoms of a substance are arranged in a repeating design. The design the tiny atoms form is the same design that shows up in a large crystal.
Quartz may form crystals so small we need a microscope to see them. Or it can grow into large crystals, and then it looks clear, sparkly and pretty.
In order for crystals to form, there must be open space within the rock so crystals have room to grow. The many flat surfaces of a crystal are known as faces.
In order for crystals to grow, conditions such as temperature need to be just right. When that happens, the crystal can grow clear and shiny.
Quartz appears in many forms. Amethyst, agate, rose quartz, rock crystal and flint are some types of quartz. Sometimes, as with amethyst or rose quartz, the crystals are so large we can see them easily. But in other forms, such as flint or agate, the quartz crystals are so tiny we can’t see them without a microscope.
The colors in the different forms of quartz come from different elements or minerals that mix with it. For example, amethyst, or purple quartz, gets its color mostly from iron mixed with the quartz. When amethyst is heated, it can turn yellow. That type of quartz is then called citrine.