Quartz                                    Mineral Group: SILICATES

Agate   Amethyst   Aventurine   Bloodstone   Carnelian   Chalcedony    Chert   Cryptocrystalline Quartz   Crystals   Drusy Quartz   Flint   Geodes   Heliotrope   Herkimer Diamonds   Jasper   Massive   Milky Quartz   Onyx   Opals   Petrified Wood   Puddingstone   Rock Crystal   Rose Quartz   Rutilated Quartz   Smoky Quartz   Thunder Eggs  Tiger's Eye
 
Quartz
  • Quartz is a very common mineral.
  • Quartz is the most common mineral found in rocks.
  • vitreous glassy luster
  • Quartz is very important in industry for making gauges, oscillators, resonators and watches.

Chalcedony is a form of cryptocrystalline quartz. Common semi-precious gemstones and rocks that are cryptocrystalline quartz or made from cryptocrystalline quartz are:

  • Agate, Aventurine, Bloodstone, Carnelian (cornelian), Chalcedony, Chert, Chrysoprase, Flint, Jasper, Onyx, Opals, Petrified Wood, Thunder Eggs
  • Some well known quartz rocks have jasper in them and have special optical properties that make them look like they glow. They are:

Silica … and the missing O
© Bert Ellison 1999 - 2002

In a recent article we read about the very common element silicon (Si), the non-metallic substance second only to oxygen, by weight, in the earth’s crust. When Si and O get together – which is most of the time – we get SiO2, quartz and perhaps other combinations.

From the swish of sand on the beach to the grind on our teeth from unwashed spinach we recognize this ubiquitous mineral. (Technically, "sand" is a size of grain and may be composed of any mineral.)

Quartz is the most common form of silica but one book lists over two dozen varieties depending on a host of impurities and crystal forms from the beauty of near-perfect hexagonal prisms with pyramidal ends to dense fibrous masses of chalcedony.

The uses for quartz in one form or another fills pages. In geology it takes on one form – alpha – at temperatures below 573° Cand beta at temperatures to 870° C. It has vast industrial use from a filler in pills – powdered form of course, to cement for concrete to the lapidarists’ favourite material. Part of this list includes: amethyst, rose, yellow, smoky, cat’s-eye, aventurine, jasper, carnelian, chrysoprase, agate onyx (true onyx not the carbonate "trade" variety), flint and many exotic varieties.

Flint and chert have been used since ancient times to chip into weapons and tools and to strike sparks for fire and firepower. Did you know that the Kakabeka Falls at Thunder Bay tumble over layers of very hard Precambrian rocks appropriately named the Gunflint Chert?

 

Quartz Varieties

 

 
 
  • citrine
 
  • drusy quartz
 
 
 
Milky Quartz
  • because of bubbles & liquids present during formation, this type of quartz turned white
  • the name comes from the fact that the colour looks like milk

Milky Quartz - piece of massive quartz
Quadville, Ontario, CANADA
 
 
 
 
 
Massive Quartz
  • Most quartz found on the earth's crust is massive - namely it is not in crystal form.
  • Quartz is one of the most common rock-building minerals.
  • It is most often found in large massive chunks. When quartz is massive, it is usually a white, milky color. It is also sometimes called milky quartz.
  • white colour is caused by gas bubbles and liquid being in the quartz as it is formed
  • This quartz sample is milky white with some glassy portions.
  • Quartz is very hard and very common.
  • Because it is hard, it will scratch many rocks.
  • Many rocks have quartz in them and that is why they are hard.
  • Quartz breaks with very sharp edges that easily scratch people and things.
 
Quartz Crystals
  • Clear quartz crystals are what most people think of when they think of a crystal.
  • When quartz is clear, it has also been called rock crystal.
  • The word crystal is derived from a Greek word meaning clear ice.
  • Quartz crystals are strongly piezoelectric, becoming polarized with a negative charge on one end and a positive charge on the other when subjected to pressure. They will vibrate if an alternating electric current is applied to them.
  • Quartz crystals are often artificially made. They are grown in labs.

Quartz    Arkansas  USA
 

 

 

 
Quartz on Flint
Flint Ridge, Ohio  USA
Quartz Crystals  from Highway 400 Roadcut, 6 Mile Lake, Ontario  CANADA

Quartz Crystal Cluster  
McKay Head, Minas Basin, Nova Scotia  CANADA
 
Coated Quartz Crystals
 
  • often quartz crystals grow in clusters and are coated by another mineral

 
Iron oxide / Hematite are common coatings found on quartz


Milky Quartz Crystals - skeletal crystal faces coated with iron oxide
Diamond Hill Mine, Antreville, South Carolina  USA


Hematite Coated Amethyst Crystals
Thunder Bay, Ontario  CANADA

Hematite stained quartz crystals
Metabetchawan, Quebec CANADA
 
Semi-Precious Quartz Gemstones
  • The quartz family is very large with a large variety of gemstone material.
  • These quartzes are crystalline.
  • They include amethyst, rose quartz
Amethyst                  

 


Amethyst pieces tumbled & polished
BRAZIL
Rutilated Quartz
  • When clear quartz has the fine needle-shaped crystals of rutile in it, it is called rutilated quartz.

   
 

Druzy Quartz
  • druzy quartz is a thin layer of small quartz crystals that coat a host rock, like a skin

 

Drusy Quartz  from Fletcher, Missouri  USA
Drusy Quartz  from Blackwell Tiff Mine, St. Francis County near Potosi, Bonne Terre, Missouri  USA

 
   
Quartz  Geodes
  • geodes are often lined with chalcesony, druzy quartz and quartz crystals
  • when the inside of a geode is filled with quartz that is not spiky crystals,
    and is rounded like mounds of grapes, then it is called botryoidal
  • Click here to find out more about geodes

  

Rose Quartz
  • Rose Quartz is pink in color, probably caused by trace amounts of manganese or titanium.
  • The Ancients believed that Rose Quartz helped women have beautiful complexions and prevented wrinkles.
  • It was also believed to open a person's heart, so that person might receive love and give love more easily.

  

Massive Rose Quartz  from Rose Quartz Quarry, Beryl Pit, Quadeville, Ontario  CANADA
Smoky Quartz
  • smoky quartz is given it's name because of its brown colour
  • Polished smoky quartz carving - a hand holding a "crystal ball
Smoky Quartz  from Little Liver lake Occurrence, Magone Rd., North of MacGregor TP, Ontario  CANADA
Chalcedony   also known as  Cryptocrystalline Quartz
  • Chalcedony can be opaque, translucent or transparent. It comes in many colors and forms.
  • Chalcedony is a cryptocrystalline quartz. It has crystals so small that a microscope is needed to see the crystal structure.

  
 

Chalcedony Nodules & Roses

Chalcedony that is whitish / pink is often found in the desert of California & Arizona

Chalcedony Geode

Chalcedony is often found in geodes. Its crystal habit, or growth pattern is often botryoidal.


 

 
Quartz - Chalcedony (fluorescent)  from Martinez lake, Arizona  USA
 
 
Pudding Stone Conglomerate  from St. Joseph's Island, Ontario  CANADA
  • puddingstone is a conglomerate with bright red and brown jasper embedded in a field of white
  • it was called puddingstone by the Pioneers who thought it looked like pudding, the jasper being like the raisins

   

Bloodstone or Heliotrope
  • Bloodstone got its name because the red spots caused by iron oxides look like drops of blood as they appear on a dark green background.

    SPECIMEN ORIGIN: BRAZIL
Chert

Banded Chert  from Lafarge Quarry, Dundas, Ontario  CANADA

  • This very hard striped rock is found in nodules or lenses in limestone. It takes a very high polish and was used by First Nation people in southern Ontario to make pipes with.

   
 

Onyx
  • Onyx is a cryptocrystalline form of quartz
  • many decorations and sculptures are made of onyx

  

Agate

 

Aventurine
Carnelian 
Flint
Opals
Petrified Wood
Thunder Eggs

Thunder Egg Geode  from Richardson's Ranch, Madras, Oregon  USA

Tiger's-Eye
 
 

 

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