What is Chalcedony?


Chalcedony is a form of silica, composed of very fine intergrowths of quartz and moganite. It’s found in various parts of the world including Brazil, Turkey, and the United States. Chalcedony comes in a variety of colors and is often used as a gemstone.

Chalcedony is a versatile gemstone that comes in a range of colors including blue, pink, and green. Its unique appearance and color make it a popular choice for jewelry and decorative items, especially beads and pendants.

Gemstone Properties

Chemical ClassificationInorganic - Silicate (Chalcedony)
ColorChalcedony comes in a variety of colors, including blue, green, pink, red, and yellow, but it's most commonly found in bluish-white or gray shades.
LusterWaxy to vitreous.
TransparencyOpaque to translucent.
OccurrenceIndia, Brazil, and Madagascar.
FormationChalcedony forms in a variety of geological settings, from cavities in volcanic rocks to sedimentary formations.
CleavagePerfect in one direction
Mohs Hardness6.5 to 7.
Specific Gravity2.58-2.64.
Diagnostic PropertiesWaxy luster, various colors.
Chemical CompositionSiO2
Crystal SystemHexagonal (variety of Quartz)
Optical PropertiesUniaxial (+)
Refractive Index1.530 - 1.539
2V angleMeasured: 58°
DispersionNot notably high.