Gemstones

Characteristics of Onyx

Characteristics of Onyx: Chemical Name: Silicon dioxide Formula: SiO2 Colors: White color-banded Structure: Trigonal Hardness: 7 Specific Gravity: 2.65 Refractive Index: 1.54-1.55 Lustre: Vitreous Streak: White Locations: India, South America,...

Characteristics of Agate

Characteristics of Agate: Chemical Name: Silicon dioxide Formula: SiO2 Colors: All colors Structure: Trigonal Hardness: 7 Specific Gravity: 2.6 Refractive Index: 1.53-1.54 Lustre: Vitreous Streak: White Locations: Worldwide, notably Brazil,...

Characteristics of Chalcedony

Characteristics of Chalcedony: Chemical Name: Silicon dioxide Formula: SiO2 Colors: All colors Structure: Hexagonal/Trigonal Hardness: 7 Specific Gravity: 2.65 Refractive Index: 1.54-1.55 Lustre: Vitreous Locations: USA, Peru, Morocco, Scotland, Netherlands,...

Characteristics of Quartz

Characteristics of Quartz: Chemical Name: Silicon dioxide Formula: SiO2 Colors: All colors Structure: Trigonal Hardness: 7 Specific Gravity: 2.65 Refractive Index: 1.54-1.55 Lustre: Vitreous Streak: White Locations: Brazil, Scotland, Spain,...

Characteristics of Howlite

Characteristics of Howlite: Chemical Name: Calcium borosilicate hydroxide Formula: Ca2B5SiO9(OH)5 Colors: White Structure: Monoclinic Hardness: 3.5 Specific Gravity: 2.6 Refractive Index: 1.58-1.61 Lustre: Subvitreous Streak: White Locations: USA, Canada, Mexico,...

Characteristics of Scheelite

Characteristics of Scheelite: Chemical Name: Calcium tungstate Formula: CaWO4 Colors: Yellow, white, pale green, orange Structure: Tetragonal Hardness: 4-4.5 Specific Gravity: 5.9-6.3 Refractive Index: 1.92-1.94 Lustre: Vitreous to greasy Streak:...