Melanophlogite is a rare, silica-based mineral that crystallizes in the cubic system, which is unusual for common SiO₂ species. Collectors prize it for its sharp, small cube-like crystals and distinct, bright blue-white fluorescence under short-wave ultraviolet light.
Is this melanophlogite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch melanophlogite with a known reference. Melanophlogite sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, brown, light yellow, dark reddish brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: encrustations.
Often confused with
Melanophlogite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Melanophlogite is noticeably harder (Mohs 6.5-7 vs. 5-5.5); luster reads adamantine on Melanophlogite and vitreous on Analcime.
How to tell apart: Luster reads adamantine on Melanophlogite and vitreous; waxy to dull when massive on Quartz.
How to tell apart: Melanophlogite is noticeably harder (Mohs 6.5-7 vs. 4); luster reads adamantine on Melanophlogite and vitreous; dull when massive on Fluorite.
Often found alongside melanophlogite
Minerals reported to co-occur with melanophlogite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- C₂H₁₇O₅·Si₄₆O₉₂
- Mohs hardness
- 6.5-7
- Density
- 1.99-2.11 g/cm³
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
- Crystal habit
- Encrustations
- Cleavage
- None
- Fluorescence
- Weak gray-white under SW UV; gray-white under LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-stage, low-temperature mineral in sulfur deposits (Racalmuto, Sicily, Italy); in low-temperature hydrothermal veins associated with metamorphosed sedimentary manganese deposits (Chvaletice, Czech Republic)
Where rockhounds find melanophlogite
Classic worldwide localities
- Mt. Hamilton, Santa Clara Co., California, USA
- Solfatara Giona, Racalmuto, and at Caltanissetta, Sicily, Italy
- Fortullino, near Quercianella, Tuscany, Italy
- Chvaletice deposit, Czech Republic
Field-hunting tip
Where it forms: A late-stage, low-temperature mineral in sulfur deposits (Racalmuto, Sicily, Italy); in low-temperature hydrothermal veins associated with metamorphosed sedimentary manganese deposits (Chvaletice, Czech Republic). If you start seeing sulfur, calcite, opal in float, you are in the right ground. Typical habit: encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify melanophlogite?+
Where is melanophlogite found?+
What rocks look like melanophlogite?+
What minerals are found with melanophlogite?+
What kind of rock does melanophlogite form in?+
What is melanophlogite used for?+
Find melanophlogite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
