Stibiotantalite is often a subject of speculation in the world of jewellery designing. Stibiotantalite is a precious mineral comprising oxygen, tantalum, antimony and niobium. However, if niobium content surpasses tantalum-based content, the mineral will be named stibiocolumbite. It appears medium-hard, translucent to transparent and yellow-to-dark-brown or even greenish/reddish brown with a luster that is akin to adamantine. Stibiotantalite is found in the walls and veins linked with tin mines. This is a mineral that is rare and owing to its comparative softness, it is likely to be discovered in mineral collections rather than jewellery. 

Many people will learn from their jewellery design course that rare stibiotantalite comes with a fascinating mixture of optical and physical attributes which help in differentiating it from other gemstones of the earth-toned variety. At the same time, cut pieces more than 2-3 carats will find a place amongst the rarest gems for collectors. 

Here are some key details of Stibiotantalite: 

• Formula- Sb(Ta, Nb) O₄
• Antimony (Sb) and Tantalum (Ta) make up their composition. 
• It occurs in granite pegmatites, more often in crystals of good quality. 
• Colours vary from dark brown to lighter and yellowish-brown, yellowish grey, reddish-yellow, greenish, reddish-brown and yellow. It is often zoned. 
• Fracture- Subconchoidal. 
• Hardness- 5-5.5. 
• Distinct 1 Direction Cleavage. 
• Crystallography- Orthorhombic, striated, crystals prismatic, often twinned, massive. 
• Refractive Index-2.37-2.46. 
• Birefringence- 0.090. 
• Dispersion- 0.146. 
• Zero Luminescence. 
• Absorption Spectrum- Non-diagnostic, may display didymium lines. 
• Optics- a = 2.37; β = 2.40; γ = 2.46. Biaxial (+), 2V=75°.
• Optic Sign- Biaxial+. 
• Luster- Vitreous-resinous. 
• Specific Gravity- 7.34-7.46. 
• Transparency- Translucent-transparent. 

Learning More About Stibiotantalite

Stibiotantalite is a part of the cervantite group of minerals and will form a series by including stibiocolumbite. The latter will result if Nb (niobium) surpasses Ta (tantalum). Stibiotantalite happens whenever the opposite takes place, i.e. when tantalite surpasses niobium. Stibiotantalite may be easily differentiated from other gems which are comparable. Yet, cut specimens largely resemble sphalerites that are commonly seen. These gems usually share a wider range of colours with earthy tones including yellow, brown, green and red tinges. Both may also be transparent and possess dispersion which surpasses diamond’s fire. This may also be quite high, going over the RI (refractive index). They also share properties of a pyroelectric nature that may leave behind yellowish streaks. 

There are some differences that still remain. Stibiotantalite usually has more hardness while sphalerites that are polished, will have more adamantine luster as compared to the former. Stibiotantalites have an appearance that varies between resinous and vitreous. Stibiotantalite comes with stronger birefringence while sphalerites do not have any. The birefringence will lend a sleepier appearance to the cut stibiotantalite owing to back facets doubling. Stibiotantalite usually has higher SG or specific gravity figures, ranging between 7.34-7.46 as compared to sphalerites. This is true for most other kinds of gemstones as well. Hence, if you come across a denser, pyroelectric, transparent and attractive gem that is earth-toned and birefringent, you will be assured of getting an extremely rare variety of stibiotantalite. Stibiotantalite is already synthesized although known jewellery uses are few in number. Enhancements also remain largely unknown. 

Discovering Stibiotantalite 

• Mozambique is known for producing the highest volume of stibiotantalite although the source may be near exhaustion in the future. 
• Other sources of such crystals include the United States (Topsham, California, San Diego County and Maine) and Brazil. 
• Western Australia’s Wodgina district churns out gem materials in the form of rolled pebbles as well. 
• Some other sources include Myanmar, Afghanistan, Russia, Kola Peninsula, Pakistan, Sri Lanka, Sweden, Zimbabwe and Varutrask. 

Sizes of Stones 

Stibiotantalites are mostly rare and cut stones exceeding 10 carats are mostly unknown. Facetable and transparent specimens are also on the rarer side. Sizes usually vary between 4.65 and 7.3. 

Care Instructions for Stibiotantalite Jewels 

Caring for this type of jewellery demands specific instructions and guidelines. You are likely to discover a higher proportion of faceted stibiotantalite within modern gem collections as compared to mainstream jewellery lineups. The 5-5.5 hardness threshold makes them more vulnerable to regular wear and tear along with scratches. They should be kept aside for special occasions and parties and kept in secure environments, separately stored from other jewellery items. Owing to inclusions within them, you should refrain from any cleaning in a mechanical way. You should rather look to use a milder detergent and warm water along with a softer brush. Always consult an expert before going ahead with the cleaning process yourself. 

Identification of Stibiotantalite

Stibiotantalite comes in several colours including greenish-yellow, brown, light yellow-brown, yellow and dark brown among others. It has fractures of a brittle nature, generating conchoidal and smaller fragments as well. The mineral has a non-magnetic type and is also non-fluorescent by way of its attributes. It has the ideal cleavage along with a light-yellowish streak and exclusive adamantine luster in tandem with an appearance varying between transparent and translucent. The average stibiotantalite density ranges between 6 and 7.4 while hardness remains at 5.5. If you are looking for reputed and highly educational jewellery design courses along with reasonable jewellery designing course fees, then you can take a look at JD Institute. Founded in the year 1988, the JD Institute of Fashion Technology is one of India’s multi-award winning and reputed design and fashion education institutions. It has a presence in several parts of the country with more than 38 learning centres and has built its own niche in design education and training while becoming an industry leader that creates industry-friendly courses. JD Institute offers numerous courses pertaining to fields like Interior Design, Fashion Design, Fashion Communication, Jewellery Design, Fashion and Lifestyle Entrepreneurship, Visual Merchandising, Fashion Business Management, Hair and Make-Up Artistry and Fashion Photography among others. JD Institute is known for offering mentoring, research, practical knowledge and classroom training. It is a great option for aspiring jewellery designers.