Ruby Mines: Mineralogy, Mining and Production

Ruby mines are deposits rich in ruby, a precious gemstone that belongs to the corundum family of minerals, the main component is aluminum oxide (Al₂O₃). The red color of rubies comes from traces of chromium, and the darker the color, the higher the value. Ruby ore belongs to the tripartite crystal system and has a high hardness of 9 on the Mohs scale, second only to diamond. Ruby has excellent abrasion and chemical resistance and has a glassy, transparent to translucent luster. Rubies are usually formed in metamorphic rocks (e.g., marble, gneiss) and igneous rocks, and are mainly symbiotic with minerals such as calcite, tremolite, and mica. Its color varies from pink to deep red, where the iron and titanium content affects its hue and transparency. The mining and processing of ruby ores require special techniques and equipment, as they are often found in association with other minerals and the ore is low in ruby content. 

Ruby Symbiotic Minerals

Ruby ores are often symbiotic with other minerals, forming complex mineral combinations. The types of these symbiotic minerals are closely related to the geological genesis of ruby ore and the type of deposit. The following are some common ruby ore symbiotic minerals:

• Corundum (Sapphire) 
  Ruby and sapphire are both corundum minerals with the same chemical composition, aluminum oxide  (Al₂O₃), but with different colors due to different coloring elements. In some deposits, ruby and sapphire can be formed at the same time, ruby is red due to the presence of chromium, while sapphire is blue due to the presence of trace elements such as iron and titanium.
• Tremolite (Ca₂Mg₅Si₈O₂₂(OH)₂)
  Tremolite is a chained silicate mineral often associated with metamorphosed marble and serpentinite. It is a member of the amphibole group, often found in calc-silicate metamorphic rocks, where rubies are formed.
• Spinel (MgAl₂O₄)
  Spinel is a magnesium-aluminum oxide that often appears in a variety of colors, including red, blue, and purple. Red spinel may resemble ruby. Both spinel and ruby are formed in high-temperature and high-pressure geological environments, especially in deposits of ultramafic and dacitic metamorphism, where they often coexist.
• Mica
  Mica is a group of layered silicate minerals that are widespread in crystalline schists and kyanites of low and intermediate metamorphism, as well as in muscovite and biotite gneisses, quartz veins, fine-grained sediments, and blue amphibole-bearing rocks. It forms with ruby veins and is especially common in metamorphic rocks such as gneisses and schists.
• Calcite(CaCO₃)
  A calcium carbonate mineral (CaCO₃), usually white or light-colored, but transparent varieties are also available. It is common in marble and the host for many metamorphic ruby deposits. Calcite is a low-hardness mineral, in marked contrast to ruby hardness.
• Garnet
  Garnet is a common class of silicate minerals that comes in a variety of colors, with common variants including red, green, and yellow. Garnets and rubies form under high temperature and pressure environments, especially in metamorphic and ultramafic environments, where they often coexist.
• Diopside(CaMgSi₂O₆)
  A calcium magnesium silicate mineral (CaMgSi₂O₆), frequently found in metamorphic marble and gabbro. In dacite, tremolite and ruby often form together, reflecting the mineral assemblage under high-temperature metamorphism.
• Rutile (TiO₂)
  Rutile is a titanium dioxide mineral that usually appears red or brown. As a common titanium mineral, it often accompanies ruby formation, especially in metamorphic deposits. As a typical inclusion in rubies, rutile is found in rubies from Burma, Mozambique, and Sri Lanka.
• Talc(Mg₃Si₄O₁₀(OH)₂)
  Talc is a very soft silicate mineral with a slippery texture and a hardness on the Mohs scale of only 1. Talc and ruby are sometimes symbiotic during metamorphism in ultramafic rock masses, especially in magnesium-bearing metamorphic zones.
• Turbidite(Ca₂Mg₅Si₈O₂₂(OH)₂)
  Turbidite is a chain silicate mineral often associated with metamorphic marble and serpentinite. In some ruby deposits, particularly in metamorphic zones of marble, tremolite and ruby can co-occur.

Ruby Mining & Production

The process of mining and producing rubies involves multiple stages, from exploration of the deposit to mining and processing of the ore. The following are the main steps in ruby mining and production:

1. Deposit exploration

Geological survey: Identification of potential ruby deposits through geological surveys and sampling. The main search is for areas of aluminum, silicon, and chromium enrichment associated with ruby formation.

Geophysical and geochemical analysis: Various geophysical techniques (e.g. electromagnetic sounding, seismic reflection, etc.) and geochemical analyses are used to assess the size and quality of the deposit.

2. Mining

Open-pit mining: Open-pit mining is usually used when ruby deposits are close to the surface. This method consists of stripping the topsoil and overburdening the rock in order to gain access to the ruby ore.

Underground Mining: When the deposit is deep, underground mining techniques are used, including the creation of shafts and adits to allow safe and efficient extraction of the ore.

Washing: The mined ore is washed or screened to remove impurities and separate the ruby-containing ore.

3. Processing

Ore crushing: The extracted ore is crushed into smaller particles for further processing.

Screening and Classification: Separate the ruby-containing ore from other ores by methods such as screening and gravity separation. Larger, better rubies are usually selected individually.

Finishing: The selected ruby ores are further polished and cut to obtain the right shape for the stone. This process is usually carried out in specialized jewelry processing plants and involves high-precision cutting and polishing.

4. Quality control

Evaluation and grading: Rubies are graded according to their color, transparency, cut quality, and size to determine their market value.

Testing: Spectral analysis, microscopic examination, and other technical means are used to ensure the authenticity and quality of rubies.

5. Marketing

Wholesale and retail: Rubies are processed and sold through jewelers, auction houses, or online marketplaces.

Branding and certification: Certification by well-known brands and organizations (e.g. GIA, etc.) can increase the market value of rubies.

6. Sustainability and environmental protection

Sustainable Mining: With the emphasis on environmental protection, many ruby miners have begun to adopt sustainable mining practices to reduce their ecological impact and improve the living conditions of the communities surrounding their mines.

The process of mining and producing rubies involves not only technology and techniques but also adherence to strict environmental regulations and social responsibility to ensure the sustainable use of resources. Refer to ruby Mines solution, you can learn more about JXSC Machine‘s related mining technology.