Where is Ruby found?
Corundum (Al₂O₃) variety Ruby
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Open the appRuby 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
Mogok Valley, Myanmar (Burma)
Historically the most famous source, known for producing the finest 'pigeon's blood' rubies from marble-hosted deposits. These rubies are highly fluorescent.
Mong Hsu, Myanmar
A significant source discovered in the 1990s, producing rubies that often require heat treatment to improve color and clarity.
Mozambique
Currently a major global source, particularly from the Montepuez deposit, producing a wide range of ruby qualities, often with good clarity and color.
Thailand (Chanthaburi, Trat)
Historically important, known for darker, brownish-red rubies, often found in basaltic host rocks. Many Thai rubies were heat-treated.
Sri Lanka (Ratnapura)
Known for producing lighter, pinkish-red rubies, often found in alluvial deposits alongside sapphires and other gemstones.
Vietnam (Luc Yen, Quy Chau)
Produces high-quality rubies, often from marble-hosted deposits, similar to those in Myanmar.
Tanzania (Winza, Longido)
Winza is known for its vibrant, often purplish-red rubies. Longido produces rubies in zoisite.
Madagascar
Various deposits, producing rubies of different qualities and colors, often requiring heat treatment.
Collecting tips
- Primary Deposits. Look for ruby in metamorphic terrains, particularly in marble, gneiss, or schist, especially where there is evidence of chromium-rich minerals or metasomatic alteration. Igneous occurrences are less common but can be found in silica-undersaturated rocks like basalt or syenite.
- Secondary (Alluvial) Deposits. Many rubies are found in placer deposits (riverbeds, ancient terraces) due to their high specific gravity and durability. Search in gravels and sands downstream from known primary sources. Panning and sieving techniques are often employed.
- Associated Minerals. Ruby can be found alongside minerals such as spinel, garnet, phlogopite mica, graphite, calcite, and various feldspars, depending on the geological environment.
- Color and Luster. Identify potential ruby by its characteristic red color and vitreous to adamantine luster. Even in rough form, the color should be distinct. Use a strong light source to observe its transparency and potential fluorescence.
- Hardness Test (Caution). While not recommended for valuable specimens, a scratch test against known minerals can help. Ruby (Mohs 9) will scratch quartz (Mohs 7) and topaz (Mohs 8). Be careful not to damage the specimen.
Quick Check
- Color:
- Red (pinkish-red to deep red)
- Luster:
- Vitreous to adamantine
- Streak:
- White
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