Ann: Lithium and Niobium Anomalies Defined at Mt Gordon, page-107

Niobium (Nb) is most commonly associated with certain elements and compounds in geological contexts, primarily due to its geochemical behavior and the types of minerals it forms. Here are the most commonly associated chemicals and elements with niobium:

1. Tantalum (Ta):

   • Association: Tantalum and niobium are chemically similar and often occur together in the same minerals, such as columbite-tantalite ((Fe,Mn)(Nb,Ta)₂O₆), commonly known as coltan. Both elements are found in pegmatites, granites, and other specialized geological environments.

2. Iron (Fe):

   • Association: Iron is a common element associated with niobium in minerals like ferrocolumbite (FeNb₂O₆) and pyrochlore ((Na,Ca)₂Nb₂O₆(OH,F)). These minerals can occur in alkaline igneous rocks and carbonatites.

3. Manganese (Mn):

   • Association: Manganese is often found in niobium-bearing minerals such as columbite and tantalite, where it can substitute for iron in the crystal structure.

4. Titanium (Ti):

   • Association: Titanium can be associated with niobium in minerals like ilmenite (FeTiO₃) and in certain niobium-titanium oxides. These associations are often found in alkaline igneous complexes and carbonatites.

5. Zirconium (Zr):

   • Association: Zirconium is often found with niobium in alkaline igneous rocks and carbonatites. Minerals like zircon (ZrSiO₄) and eudialyte ((Na,Ca)₆(Fe,Mn)₂(Zr,Nb)₃Si₆O₁₇(OH,Cl)₂) can contain both elements.

6. Rare Earth Elements (REEs):

   • Association: Rare earth elements, such as cerium (Ce), lanthanum (La), and yttrium (Y), can be associated with niobium in certain mineral deposits, particularly in carbonatites and alkaline igneous complexes.

7. Alkali Metals (e.g., Sodium (Na), Potassium (K)):

   • Association: These elements are often found in niobium-bearing minerals in alkaline igneous rocks and carbonatites. Minerals like pyrochlore and loparite ((Ce,Na,Ca)(Ti,Nb)O₃) can contain significant amounts of sodium and potassium.

8. Phosphorus (P):

   • Association: Phosphorus is commonly associated with niobium in phosphate minerals such as apatite ((Ca₅(PO₄)₃(F,Cl,OH))), which can occur in carbonatites and other phosphate-rich environments.

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Aluminum Oxide (Al2O3):

• Association: Aluminum is common in many igneous and metamorphic minerals. Niobium can occur in complex aluminum-silicate minerals, especially in pegmatitic environments.

Silicon Dioxide (SiO2):

• Association: Silicon dioxide is a major component of many igneous rocks and can be present in the same environments where niobium is found, especially in silicate minerals within pegmatites and alkaline igneous complexes.

Titanium Dioxide (TiO2):

• Association: Titanium and niobium often occur together in minerals such as ilmenite and titanite. Pyrochlore, a niobium mineral, can also contain titanium.

Loss on Ignition (LOI1000):

• Association: Loss on ignition at 1000°C (LOI1000) measures the amount of weight loss when a sample is heated, indicating the presence of volatiles such as water, carbon dioxide, or other gases. High LOI values can be associated with alteration minerals or carbonatites, which can host niobium mineralization.

Typical LOI1000 Values:

• Low LOI1000 Values: Generally, values below 2-3% are considered low. These indicate samples with minimal volatiles, suggesting a composition dominated by stable minerals with little organic matter or volatile content.

• Moderate LOI1000 Values: Values ranging from 3% to 10% are considered moderate. This range might indicate the presence of some hydrated minerals, carbonates, or organic matter.

• High LOI1000 Values: Values above 10% are considered high. High LOI1000 values indicate significant amounts of volatile components, which could include water in hydrated minerals (e.g., clays), carbonates (which release CO2 upon heating), or substantial organic matter content.