Quartz – lots of looks, one cool mineral

Quartz is the most common mineral found in the Earth’s crust.  Fairly hard, quartz is a 7 on the Mohs hardness scale which has a range from Quartz double point crystals1 (softest) to 10 (hardest).  Quartz, which is sometimes called “Rock Crystal,” is often colorless and has a glassy (shiny) appearance.  Quartz has a white streak when rubbed on a streak plate; however, due to its hardness, the streak is often hard to see unless you press very hard on the plate. 

 Well formed crystals of the mineral are often found in clusters, which is also called ‘druse,’ and commonly form in geodes and in veins and show a single point at one end.  When a quartz crystal shows points on both ends it is often called a Herkimer Diamond.  These crystals are somewhat rare because in order to form with these double points, the quartz must have very little contact with the surrounding rock while the crystal is being formed.  The term Herkimer Diamond can only truly be used with sample found in Herkimer County, New York, although double point quartz crystals have been found in other locations throughout the world. 

 Amethyst CrystalsQuartz is a major component of most of the Earth’s rocks and is found in many varities of igneous, sedimentary and metamorphic rocks.  In addition to the colorless, Rock Crystal form, Quartz comes in many varieties such as amethyst (purple), citrine (brown), rose quartz (pink), milky quartz (white), smoky quartz (gray), chert and agate (many colors but very small crystals) to name just a few.  The mineral quartz is commonly used in technology such as televisions, watches and clocks.

2 Responses to “Quartz – lots of looks, one cool mineral”

  1. thanks you so much but whats its cleavage and fracture

  2. Quartz does not have cleavage. When the crystal is broken, it has a conchoidal fracture.

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