Where is Ruby in Zoisite found?
Corundum (Ruby) in Zoisite
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Open the appRuby in Zoisite 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 Ruby in Zoisite
Tanzania
The primary and most famous source, particularly the Longido mining district near Mount Kilimanjaro. This is where the material was first discovered and named Anyolite.
India
Some occurrences have been reported, though less prominent than Tanzanian material.
Kenya
Similar geological settings to Tanzania, with some reported finds.
Norway
Minor occurrences of zoisite with corundum have been noted.
Collecting tips
- Geological Context. Look for areas with evidence of metasomatism where felsic intrusions have interacted with chromium-rich mafic or ultramafic rocks.
- Color Recognition. The distinctive green, red, and black coloration is a key identifier. The red ruby stands out against the green zoisite.
- Hardness Test. Ruby (9 on Mohs) will scratch zoisite (6-6.5 on Mohs) and amphibole (5-6 on Mohs). This can help confirm the presence of ruby.
- Associated Minerals. Often found with other metamorphic minerals characteristic of the host rock and metasomatic alteration.
Quick Check
- Color:
- Green (zoisite), red (ruby), black (amphibole)
- Luster:
- Vitreous to pearly (zoisite), adamantine to vitreous (ruby), vitreous to dull (amphibole)
- Streak:
- White (zoisite), white (ruby), grayish-white (amphibole)
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