Where is Ruby found?
Corundum (Al₂O₃) var. 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 important source, known for producing the finest 'pigeon's blood' rubies from marble deposits.
Mong Hsu, Myanmar
A significant source discovered in the 1990s, producing heat-treatable rubies.
Mozambique
Currently a major global source, with large deposits yielding high-quality rubies from amphibolite-hosted occurrences.
Thailand (Chanthaburi, Trat)
Known for dark red to brownish-red rubies, often found in basaltic host rocks and alluvial deposits.
Sri Lanka (Ratnapura)
Produces a range of ruby colors, often lighter red to pinkish-red, from alluvial gravels.
Tanzania (Winza, Longido)
Winza is known for vibrant, unheated rubies. Longido produces rubies in zoisite.
Madagascar
Various deposits yielding rubies of different qualities and colors.
Vietnam (Luc Yen, Quy Chau)
Produces fine rubies from marble-hosted deposits, similar to Myanmar.
Collecting tips
- Geological Context. Focus on areas known for metamorphic rocks (marbles, gneisses, schists) or igneous rocks (basalts, syenites) that are aluminum-rich and silica-poor. Alluvial deposits downstream from such primary sources are also prime locations.
- Hardness Test. Ruby is very hard (9 on Mohs scale). It will scratch quartz (7) and most other common minerals. This is a key differentiating factor from many red look-alikes.
- Specific Gravity. Rubies are relatively dense (3.97-4.05 g/cm³). Panning in alluvial deposits can help concentrate heavier minerals like ruby.
- Crystal Habit. Look for hexagonal prismatic or tabular crystals, or fragments with characteristic parting planes. In alluvial deposits, they will be rounded but retain their density and hardness.
- Fluorescence. Many rubies exhibit strong red fluorescence under long-wave UV light due to chromium, which can aid in identification, especially in rough material.
- Associated Minerals. In primary deposits, rubies are often found with minerals like phlogopite, spinel, graphite, calcite, dolomite, and various amphiboles or feldspars, depending on the host rock.
Quick Check
- Color:
- Red (pinkish-red to deep red)
- Luster:
- Vitreous to adamantine
- Streak:
- White
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