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This combination refers to three distinct mineral varieties often used together in jewelry, particularly as beads. Amazonite is a blue-green variety of microcline feldspar. Carnelian is a reddish-orange to brownish-red variety of chalcedony (cryptocrystalline quartz). Citrine is a yellow to orange-brown variety of macrocrystalline quartz. Each possesses unique physical and chemical properties, contributing to their distinct appearances and uses.
How to Identify
- Color
- Amazonite: Distinctive blue-green to green. Carnelian: Translucent reddish-orange to brownish-red. Citrine: Transparent yellow to orange-brown.
- Luster
- Amazonite: Vitreous to pearly. Carnelian: Waxy to vitreous. Citrine: Vitreous.
- Texture
- Amazonite: Smooth, often with fine striations. Carnelian: Smooth, often conchoidal fracture surfaces. Citrine: Smooth, glassy.
- Crystal Form
- Amazonite: Typically anhedral to subhedral masses, sometimes prismatic crystals. Carnelian: Cryptocrystalline aggregates, massive. Citrine: Prismatic hexagonal crystals, often in geodes or drusy coatings.
- Cleavage
- Amazonite: Perfect in two directions at nearly 90 degrees. Carnelian: None (cryptocrystalline). Citrine: None (conchoidal fracture).
- Geological Environment
- Amazonite: Granitic pegmatites, syenites, and some hydrothermal veins. Carnelian: Volcanic rocks, sedimentary deposits (e.g., geodes, nodules), hydrothermal veins. Citrine: Hydrothermal veins, pegmatites, igneous and metamorphic rocks, often found in geodes.
Key Facts
- Hardness: Amazonite: 6-6.5 (Mohs); Carnelian: 6.5-7 (Mohs); Citrine: 7 (Mohs)
- Specific Gravity: Amazonite: 2.56-2.58; Carnelian: 2.58-2.64; Citrine: 2.65
- Crystal System: Amazonite: Triclinic; Carnelian: Trigonal (cryptocrystalline); Citrine: Trigonal
- Color: Amazonite: Blue-green, green; Carnelian: Reddish-orange, brownish-red; Citrine: Yellow, orange-brown
- Luster: Amazonite: Vitreous to pearly; Carnelian: Waxy to vitreous; Citrine: Vitreous
- Transparency: Amazonite: Translucent to opaque; Carnelian: Translucent; Citrine: Transparent
- Fracture: Amazonite: Uneven to conchoidal; Carnelian: Conchoidal; Citrine: Conchoidal
- Cleavage: Amazonite: Perfect in two directions at nearly 90 degrees; Carnelian: None; Citrine: None
- Composition: Amazonite: Potassium aluminum silicate; Carnelian: Silicon dioxide; Citrine: Silicon dioxide
Quick Check
- Color: Amazonite: Blue-green; Carnelian: Reddish-orange; Citrine: Yellow to orange-brown
- Luster: Amazonite: Vitreous to pearly; Carnelian: Waxy to vitreous; Citrine: Vitreous
- Streak: All three: White
Physical Characteristics
- Crystal Habit: Amazonite: Prismatic, massive; Carnelian: Massive, botryoidal, stalactitic; Citrine: Prismatic, massive, drusy
- Cleavage Type: Amazonite: Perfect {001} and {010}; Carnelian: Not applicable; Citrine: Not applicable
- Fracture Type: Amazonite: Uneven to conchoidal; Carnelian: Conchoidal; Citrine: Conchoidal
- Tenacity: Amazonite: Brittle; Carnelian: Tough; Citrine: Brittle
- Luster Type: Amazonite: Vitreous to pearly; Carnelian: Waxy to vitreous; Citrine: Vitreous
Formation
Amazonite forms in granitic pegmatites and some hydrothermal veins. Carnelian and Citrine are varieties of quartz, forming in igneous, metamorphic, and sedimentary environments. Carnelian's color is due to iron oxide impurities, while Citrine's color is due to iron impurities, often enhanced by natural or artificial heat treatment.
Usage
Primarily used as gemstones for jewelry (beads, cabochons, faceted stones), ornamental objects, and decorative carvings. Historically, they have been used for seals, intaglios, and amulets.
Age Distribution
Formed throughout various geological eras, depending on the specific geological processes involved.
Where to Find
Amazonite
Notable localities include Russia (Ilmen Mountains), USA (Colorado, Virginia), Brazil, Madagascar, and Canada.
Carnelian
Found in India (Maharashtra), Brazil, Uruguay, USA (Oregon, Washington), and Madagascar.
Citrine
Major sources include Brazil (Minas Gerais), Bolivia, Russia (Ural Mountains), Madagascar, and Spain.
Finding Tips
Amazonite Prospecting
Look for granitic pegmatites, especially those with other feldspars, quartz, and mica. Amazonite often occurs in large, blocky masses within these formations. Its distinctive blue-green color makes it relatively easy to spot.
Carnelian Prospecting
Search in areas with volcanic activity or sedimentary deposits. Carnelian can be found as nodules, geodes, or vein fillings. Look for translucent reddish-orange to brownish-red chalcedony in riverbeds or weathered outcrops.
Citrine Prospecting
Explore pegmatites and hydrothermal veins. Citrine often forms in association with amethyst and other quartz varieties. Look for transparent yellow to orange-brown quartz crystals in vugs or geodes. Be aware that much commercial citrine is heat-treated amethyst.
Safety Precautions
When collecting, always wear appropriate safety gear, including eye protection and gloves. Be mindful of unstable rock formations and potential hazards in mining or quarry environments. None of these minerals are inherently toxic, but inhaling fine dust from cutting or grinding any mineral should be avoided by wearing a respirator.
Similar Rocks
Turquoise
CuAl6(PO4)4(OH)8·4H2O
Also known as: Callais
Jasper
SiO2 (cryptocrystalline quartz)
Also known as: Picture Jasper, Red Jasper
Topaz
Al2SiO4(F,OH)2
Also known as: Imperial Topaz, Sherry Topaz
Scientific Classification
- Mineral Class
- Amazonite: Tectosilicate; Carnelian: Tectosilicate (Chalcedony group); Citrine: Tectosilicate (Quartz group)
- Group
- Amazonite: Feldspar group (Microcline variety); Carnelian: Chalcedony group (Quartz variety); Citrine: Quartz group
- Crystal System
- Amazonite: Triclinic; Carnelian: Trigonal (cryptocrystalline); Citrine: Trigonal
- Chemical Formula
- Amazonite: KAlSi3O8; Carnelian: SiO2; Citrine: SiO2
- Composition
- Amazonite: Potassium aluminum silicate; Carnelian: Silicon dioxide with iron oxide impurities; Citrine: Silicon dioxide with iron impurities
Explore Amazonite, Carnelian, Citrine
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