World of Dinosaurs/Mineralogy/Quartz

Quartz is composed of silica and oxygen.

Here is a 3D model of a quartz crystal.

Attributes

 * Quartz is usually totally transparent, with a glassy luster.
 * It often forms beautiful crystals, like in geodes.
 * It is hard to scratch and hard to dissolve, but it can break if you smash it.
 * The reason for this strength is the regular crystal structure within the mineral.
 * The silicon and oxygen atoms help form this structure.
 * The atoms maintain a repeating structure throughout 3D space.
 * The atoms are joined by covalent bonds.
 * Quartz can be broken with something like a hammer and the pieces will look like broken glass.


 * The process of weathering, erosion, and transportation can break down quartz crystals that then build up on beaches as sand. These later form sandstone layers.

Where to find Quartz and how it's formed
Quartz forms naturally without help from life.


 * Quartz can form in large and beautiful crystals in caves or geodes.
 * If the crystal has color it has chemical impurities in its structure that cause light to bend through the crystal.
 * These colored variations can have their own gemstone names such as: smokey quartz, amethyst, citrine, etc.
 * Quartz can form as crystals in magma or lava.
 * In lava rocks that cool quickly the quartz crystals will not have observable crystals.
 * Examples include obsidian and pumice.
 * In magma that cools slowly the crystals can grow large enough to be seen.
 * Examples include granite, diorite, etc.
 * Quartz can also be dissolved in water.
 * If this water has specific chemical then quartz can form:
 * in cracks between other minerals or sand grains;
 * or by dissolving other minerals and then using their parts to make quartz elsewhere;
 * or it can replace whole seashells, leaving incredibly detailed glass-like fossils.

Importance of Quartz

 * Quartz is incredibly important for sedimentary rocks.
 * For example, sandy beaches in California, Oregon, and Washington include lots of quartz grains.
 * These grains were formed by:
 * weathering the original rocks the quartz came from (maybe a granite);
 * transporting the quartz pieces a long distance, possibly through a river;
 * eroding the quartz pieces as they collide and break for years as they move along the riverbed;
 * further eroding the quartz as they collide on the beach.

In the right conditions, sand can eventually form sandstone.