Table of Contents
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Amazonite
Apatite
Aragonite
Calcite
Celestite
Feldspar
Fluorite
Fossils
Amber
Jet
Stromatolite
Glass
Obsidian
Hemitite
Howlite
Kyanite
Quartz
Attributes
Crystal System: Hexagonal
Composition: Silicone and Oxygen (SiO2)
Crystal habit: 6-sided prism ending in 6-sided pyramid (typical), drusy, fine-grained to microcrystalline, massive
Mohs hardness: 7
Luster: Vitreous – waxy to dull when massive
Diaphaneity: Transparent to opaque
Solubility: Insoluble
Grows in "twinned" pairs in opposite slanted directions, causing a bed of quartz to be a knot work of crystals. Large flawless specimens are artificially grown.
Macrocrystalline
Diaphaneity: Transparent
Clear Quartz Crystal
Also known: Rock crystal
Color: Colorless
Rutilated Quartz
Contains needle-like inclusions of rutile
Herkimer Diamond
Color: Colorless
Citrine
Physical Attributes
Color: Yellow to reddish orange or brown. Occasionally greenish yellow.
Location: Primarily Brazil
Commercially sold citrine is usually heat treated amethyst.
Metaphysical Attributes
Also known as "merchant's stone" or "money stone" because it brings prosperity.[5]
Amethyst
Color: Purple to violet
Location: Brazil, Mexico, Uruguay, Russia, France, Namibia and Morocco
Ametrine
Color: Mixed amethyst and citrine hues
Amethyst and citrine are often found on the same bed and can blend together into ametrine.
Rose Quartz
Color: Pink
May display diasterism from microscopic rutile.
Color comes from trace amounts of titanium, iron, or manganese.
Smoky Quartz
Color: Shades of gray, sometimes brown or black
Diaphaneity: Transparent to opaque
Microcrystalline
Aventurine
Tiny inclusions (usually mica) creating aventurescence
Diaphaneity: Translucent to opaque
Cryptocrystalline
Fibrous
Diaphaneity: Translucent to opaque
Chalcedony
Color: Various. White and light colors are simply classified as "chalcedony" while other colors are given specific names.
Carnelian
Color: Reddish orange
Widely heat treated to deepen color.
Dumortierite quartz
Color: Blue, sometimes purple or gray
Contrasting dark and light zones
Milky Quartz
Color: White
May have diasterism. Contains minute fluid inclusions of gas, liquid, or both, trapped during crystal formation. [6]
Prasiolite
Also known: Vermarine
Color: Mint or olive green
Location: Brazil, Poland, Canada
Rare. Commercially sold green quartz is usually heat treated amethyst.
Tiger's Eye
Color: Fibrous gold, red-brown, or bluish
Exhibits chatoyancy
Agate
Color: Bands of various color
Diaphaneity: At least one band is translucent
Onyx
Color: Straight bands of color
Jasper
Color: Various
Diaphaneity: Opaque
Ruby
Selenite
Shungite
Stone
It is incredibly difficult to classify the relationships between the different types of quartz, especially when scientific and colloquial definitions are at odds.
Chalcedony and cryptocrystalline refer to the same quartz qualities, but here I separate the terms leaving chalcedony to only refer to single colored cryptocrystalline rocks.
Microcrystalline is an umbrella term that includes cryptocrystalline, but here I separate it to mean translucent rocks with notable inclusions.
I've defined the general quartz taxonomy as this:
- Macrocrystalline: Transparent
- Microcrystalline: Translucent or opaque with notable inclusions
- Cryptocrystalline: Translucent or opaque
- Chalcedony: Single color translucent
- Agate: Banded colors, at least one translucent
- Jasper: Opaque