Description
Overview and Key Features
This exquisite Bixbyite Crystals on Topaz Mineral Specimen originates from the world-renowned Topaz Mountain in the Thomas Range, Juab County, Utah, USA — one of the most celebrated localities for gem-quality Topaz and rare Bixbyite combinations. This exceptional piece features lustrous, metallic-black Bixbyite crystals perfectly perched on a transparent to pale champagne Topaz matrix, forming a visually striking and scientifically significant mineral pairing.
All of our Fossils are 100% Genuine Specimens and come with a Certificate of Authenticity. Each specimen is carefully selected for its clarity, aesthetic crystal arrangement, and geological importance. The accompanying photo shows the actual specimen you will receive, alongside a 1cm scale cube for accurate sizing.
Geological Classification and Composition
Bixbyite is a manganese iron oxide mineral, with the chemical formula (Mn,Fe)₂O₃, belonging to the oxide mineral class. It crystallises in the isometric system, typically forming well-defined cubic or octahedral crystals with a bright metallic lustre. The mineral is named after Maynard Bixby, who first discovered it at Topaz Mountain in 1897.
The Topaz on which the Bixbyite rests is a fluoro-silicate mineral, with the chemical formula Al₂SiO₄(F,OH)₂, belonging to the silicate mineral class. Topaz forms through pneumatolytic processes, typically in rhyolitic volcanic cavities, where volatile-rich gases allow crystal growth in open pockets (vugs). This geological environment provides the perfect conditions for both Bixbyite and Topaz to crystallise side by side.
Scientific Details:
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Bixbyite Formula: (Mn,Fe)₂O₃
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Crystal System: Isometric
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Hardness: 6 – 6.5 (Mohs scale)
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Lustre: Metallic to submetallic
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Colour: Deep black to steel-grey
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Transparency: Opaque
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Specific Gravity: 4.9 – 5.0
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Topaz Formula: Al₂SiO₄(F,OH)₂
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Crystal System: Orthorhombic
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Hardness: 8 (Mohs scale)
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Lustre: Vitreous
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Transparency: Transparent to translucent
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Cleavage: Perfect basal {001}
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Specific Gravity: 3.4 – 3.6
This specimen beautifully illustrates the natural contrast between Topaz’s clear vitreous structure and Bixbyite’s reflective metallic cubes, a combination that has made Topaz Mountain material highly sought after by mineral collectors worldwide.
Geological Formation and Locality
The Topaz Mountain region lies within the Thomas Range volcanic field of central Utah, part of a late Tertiary rhyolitic system rich in fluorine-bearing gases. Around 6–7 million years ago, these rhyolitic lava flows cooled and crystallised, leaving behind gas-filled cavities and fumarolic pockets lined with gem-quality minerals.
Within these cavities, fluorine and silica vapours combined to form Topaz crystals, while iron and manganese oxides precipitated as Bixbyite. Over time, hydrothermal activity introduced trace elements and vapours that created ideal growth environments for both minerals, often resulting in aesthetic combinations like the one offered here.
The Topaz Mountain locality is also famous for associated minerals such as Red Beryl (Bixbite), Pseudobrookite, Hematite, Quartz, Garnet, and Sanidine, making it one of the richest and most geologically diverse rhyolite outcrops in North America.
These Bixbyite on Topaz specimens are often discovered embedded in rhyolite nodules or loose within alluvial deposits surrounding the main flow domes. Their distinct pairing captures a moment of high-temperature crystallisation preserved over millions of years — a testament to the geological artistry of nature.
Morphology and Visual Features
This specimen exhibits sharp, well-defined octahedral Bixbyite crystals with mirror-like metallic lustre, contrasting elegantly against the pale, translucent Topaz base. The Bixbyite crystals often show striations and complex twinning patterns under magnification, evidence of multiple growth phases within fluctuating temperature and pressure conditions.
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Bixbyite Crystals: Octahedral, metallic, deep jet-black with reflective faces.
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Topaz Host: Transparent to golden-hued matrix, glassy and prismatic.
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Crystal Relationship: Bixbyite epitaxially attached to Topaz surfaces, highlighting natural symmetry and mineral association.
Under direct light, the Bixbyite reflects metallic flashes of silver-grey, while the Topaz displays subtle internal refraction and a delicate champagne tone. Together, they form a naturally harmonious mineral composition that appeals equally to collectors, geologists, and enthusiasts of aesthetic mineralogy.
Scientific and Mineralogical Significance
From a mineralogical standpoint, Bixbyite is a rare oxide mineral that provides valuable insights into volcanic fumarolic crystallisation and oxidation-reduction equilibria in rhyolitic systems. The manganese-to-iron ratio within the crystals can reveal the redox state of the magmatic fluids during formation, making such specimens useful in petrogenetic studies.
Meanwhile, Topaz serves as a geochemical indicator of fluorine-rich magmatic systems, often marking the late-stage crystallisation of granitic and rhyolitic magma chambers. When found together, these minerals represent two complementary phases of the same geochemical system — Bixbyite reflecting metallic oxide precipitation and Topaz recording the volatile silica-fluorine environment that crystallised afterward.
Together, they showcase the interplay between metallic and silicate mineralisation within a high-temperature, vapour-dominated system — a geological rarity that bridges igneous and pneumatolytic processes.
Collector, Display, and Educational Value
This Bixbyite on Topaz Specimen from Topaz Mountain, Utah is a museum-grade mineral association admired for both its rarity and its striking aesthetic. Its contrasting textures — metallic and glassy — demonstrate mineralogical harmony and crystallographic precision in their purest form.
Collectors value these specimens for their clarity, crystal sharpness, and provenance, while educators prize them for their demonstration of volcanic cavity mineralisation and oxide-silicate relationships. When displayed under strong lighting, the specimen’s reflective surfaces and clarity become even more pronounced, highlighting the complexity and beauty of natural mineral growth.
To maintain its natural lustre, handle gently and avoid prolonged exposure to moisture or acids. Clean only with a soft, dry cloth.
A truly exceptional specimen, this Bixbyite Crystals on Topaz from Topaz Mountain, Utah captures a perfect moment of volcanic mineral evolution — uniting the brilliance of metallic Bixbyite with the luminous clarity of Topaz in one remarkable piece of natural history.
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