Where is Calcite, Sugilite found?
Calcite (CaCO3), Sugilite (KNa2(Fe,Mn,Al)2Li3Si12O30)
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Open the appCalcite, Sugilite 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 Calcite, Sugilite
Calcite: Worldwide
Calcite is one of the most common minerals on Earth, found in virtually every geological setting. Notable occurrences include the 'Iceland spar' variety from Iceland, large crystals from Mexico, and various forms in caves globally.
Sugilite: Wessels Mine, Northern Cape, South Africa
The primary and most significant source of gem-quality sugilite. It occurs in a manganese mine within a highly metamorphosed and metasomatized sequence of iron-formation and carbonate rocks.
Sugilite: Iwagi Islet, Ehime Prefecture, Japan
The type locality for sugilite, where it was first discovered in 1944. Occurs in an aegirine syenite.
Sugilite: Mont Saint-Hilaire, Quebec, Canada
Known for producing small, well-formed sugilite crystals in an alkaline intrusive complex.
Sugilite: Liguria, Italy
Occurrences reported in manganese deposits.
Collecting tips
- Calcite: Acid Test. Calcite effervesces vigorously in dilute hydrochloric acid (HCl). This is a key diagnostic test. Sugilite does not react with acid.
- Calcite: Double Refraction. Transparent calcite (Iceland spar) exhibits strong double refraction, where a single line viewed through the crystal appears as two.
- Sugilite: Color and Hardness. Look for the distinctive purple color. Its hardness (5.5-6.5) is higher than many other purple minerals, which can help differentiate it.
- Sugilite: Associated Minerals. Sugilite is often found with other manganese minerals (e.g., braunite, kutnahorite, rhodochrosite) and alkali-rich minerals.
Quick Check
- Color:
- Calcite: White, colorless, or various hues; Sugilite: Purple, reddish-purple, violet.
- Luster:
- Calcite: Vitreous to pearly; Sugilite: Vitreous to resinous.
- Streak:
- Calcite: White; Sugilite: White to pale purple.
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