Where is Amazonite and Orange Calcite found?
Amazonite (variety of Microcline, KAlSi3O8) and Orange Calcite (CaCO3)
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Open the appAmazonite and Orange Calcite occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Amazonite and Orange Calcite
Amazonite: Pikes Peak, Colorado, USA
Renowned for producing some of the finest deep blue-green amazonite crystals, often associated with smoky quartz.
Amazonite: Minas Gerais, Brazil
Significant source of amazonite, often found in large masses and crystals within pegmatite deposits.
Amazonite: Ilmen Mountains, Russia
Historical source of high-quality amazonite, particularly from the Ural Mountains region.
Amazonite: Amelia Courthouse, Virginia, USA
Known for its pegmatite deposits yielding amazonite and other feldspar minerals.
Orange Calcite: Mexico
Major producer of orange calcite, often found in large, translucent masses suitable for carving.
Orange Calcite: USA (various states)
Found in numerous localities, particularly in limestone caves (e.g., Missouri, Arkansas) and hydrothermal deposits.
Orange Calcite: China
Significant source of various calcite forms, including orange varieties, often from mining operations.
Orange Calcite: Peru
Known for its diverse mineral deposits, including occurrences of orange calcite.
Collecting tips
- Amazonite in Pegmatites. Look for amazonite in granitic pegmatite dikes. These are often found in areas with significant igneous activity and can be identified by their unusually large crystal sizes and diverse mineral assemblages. Search for areas with exposed bedrock or old mine dumps.
- Orange Calcite in Sedimentary and Hydrothermal Settings. Orange calcite can be found in limestone quarries, caves, and areas with hydrothermal alteration. In caves, look for stalactites, stalagmites, and flowstone. In sedimentary environments, it may occur as veins or replacement minerals. Always obtain permission before entering private land or caves.
- Color and Luster Identification. Amazonite's distinct blue-green color is a primary identifier. Orange calcite's vibrant orange hue and vitreous luster are key. Be aware that both minerals can have variations in color intensity.
- Cleavage Test. For Amazonite, observe the two perfect cleavages at nearly 90 degrees. For Orange Calcite, the perfect rhombohedral cleavage is a definitive test; a small piece will break into rhomb-shaped fragments. This can be done carefully with a rock hammer or by observing natural breaks.
- Hardness Test (for differentiation). Amazonite (6-6.5 on Mohs scale) is significantly harder than Orange Calcite (3 on Mohs scale). Amazonite will scratch glass, while calcite will not and can be scratched by a copper coin. This is a crucial differentiating factor.
- Acid Test (for Calcite). Orange Calcite will effervesce (fizz) vigorously when a drop of dilute hydrochloric acid (HCl) is applied to its surface, due to the release of carbon dioxide. Amazonite will not react to acid. Always handle acids with extreme caution and appropriate safety gear.
Quick Check
- Color:
- Amazonite: Blue-green to green. Orange Calcite: Orange to yellowish-orange.
- Luster:
- Amazonite: Vitreous to pearly. Orange Calcite: Vitreous to resinous.
- Streak:
- Amazonite: White. Orange Calcite: White.
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