If you are fascinated by the hidden structures of our planet, you have likely come across
STILLWELLITE-(Ce). This mineral is a compelling subject for study, offering a unique glimpse into the complex chemistry that shapes the Earth’s crust.Whether you are a student identifying a hand sample, a researcher looking for crystallographic data, or a collector curious about a new find, this guide breaks down everything you need to know about
STILLWELLITE-(Ce). From its precise chemical formula to the geological environments where it thrives, let’s explore what makes this mineral distinct.
The Chemistry Behind the Crystal
Every mineral tells a story through its chemistry. At its core,
STILLWELLITE-(Ce) is defined by the chemical formula
CeB[SiO4]O.This isn’t just a string of letters and numbers; it represents the precise recipe of elements that nature used to build this specimen. This specific chemical composition is what gives the mineral its stability and dictates how it reacts with acids, heat, or other minerals. It is the fundamental “DNA” that geologists use to classify it within the larger mineral kingdom.
Crystallography: Geometry in Nature
One of the most beautiful aspects of mineralogy is the hidden geometry within every stone.
STILLWELLITE-(Ce) crystallizes in the
Hexagonal-Trigonal system.Think of this as the mineral’s architectural blueprint. It dictates the symmetry and the angles at which the crystal faces grow. Digging deeper into its symmetry, it falls under the
Trigonal pyramidal.
- Point Group: 3
- Space Group: P31
Why does this matter? These crystallographic details are like a fingerprint. They influence optical properties—how light travels through the crystal—and physical traits like how it breaks or cleaves when struck.
Internal Structure and Unit Cell
If we could zoom in to the atomic level, we would see the “Unit Cell”—the smallest repeating box of atoms that builds up the entire crystal. For
STILLWELLITE-(Ce), the dimensions of this microscopic building block are:
a=6.84Å, c=6.70Å, Z=3
The internal arrangement of these atoms is described as:
Nesosilicates: insular SiO4 tetrahedra with BO3 triangles &/or B[4], Be[4] tetrahedra, cornersharing with SiO4 tetrahedra; helical chains // [0001] of 3-membered rings consisting of 2 BO4 tetrahedra & 1 SiO4 tetrahedron, chains linked by (Ce,La)O9 polyhedra.1 Combo chain & insular patterns; spiral chains of B tetrahedra extend along c axis & are surrounded by Si tetrahedra; btw chains, above & below Si tetrahedra, lie Ce atoms in irregular polyhedra (CN = 9), which form heterogeneous columns in same direction.2 Typified by columns of Si tetrahedra & Ce 9-pointed fig alternating along z axis; columns are interlayed by helical chains of BO4 tetrahedra extending in same direction.3 Contains helical chains of (BO4) tetrahedra polymerized by sharing corners; these chains are decorated by (SiO4) tetrahedra that share 2 corners with adjacent (BO4) tetrahedra; large, irregular [9]-coordinate REE sites link polyhedral chains.3This internal structure is the invisible framework that supports everything we see on the outside, from the mineral’s density to its hardness.
Physical Appearance (Habit)
When you find
STILLWELLITE-(Ce) in the field, what does it actually look like? A mineral’s “habit” describes its typical shape and growth pattern.
- Common Habit: As flat rhombohedral macro crystals and massive
- Twinning: Observed about [100]
Twinning is a fascinating phenomenon where two or more crystals grow interlocked in a specific symmetrical pattern. If STILLWELLITE-(Ce) exhibits twinning, it can be a dead giveaway for identification, distinguishing it from look-alike minerals.
Where is it Found? (Geologic Occurrence)
Minerals are the products of their environment. They don’t just appear anywhere; they need specific conditions—pressure, temperature, and chemical ingredients—to form.
Geologic Occurrence:
Metasomatic replacement of metamorphosed calcareous sediments; in alkalic pegmatites in syenite in alkalic massifKnowing this context helps geologists reconstruct the history of a rock formation. It tells us whether the rock was born from cooling magma, settled in an ancient ocean, or was transformed by the intense heat and pressure of metamorphism. For more broad geological context, resources like the
U.S. Geological Survey (USGS) provide excellent maps and data.
Related Minerals
No mineral exists in a vacuum.
STILLWELLITE-(Ce) is often related to other species, either through similar chemistry or structure.
Relationship Data:
Related to datolite-gadolinite groupUnderstanding these relationships is key. It helps us see the “family tree” of the mineral world, showing how different elements can substitute for one another to create an entirely new species with similar properties.
Frequently Asked Questions (FAQs)
1. What is the chemical formula of STILLWELLITE-(Ce)?The standard chemical formula for STILLWELLITE-(Ce) is
CeB[SiO4]O. This defines its elemental composition.
2. Which crystal system does STILLWELLITE-(Ce) belong to?STILLWELLITE-(Ce) crystallizes in the
Hexagonal-Trigonal system. Its internal symmetry is further classified under the Trigonal pyramidal class.
3. How is STILLWELLITE-(Ce) typically found in nature?The “habit” or typical appearance of STILLWELLITE-(Ce) is described as
As flat rhombohedral macro crystals and massive. This refers to the shape the crystals take when they grow without obstruction.
4. In what geological environments does STILLWELLITE-(Ce) form?STILLWELLITE-(Ce) is typically found in environments described as:
Metasomatic replacement of metamorphosed calcareous sediments; in alkalic pegmatites in syenite in alkalic massif. This gives clues to the geological history of the area where it is discovered.
5. Are there other minerals related to STILLWELLITE-(Ce)?Yes, it is often associated with or related to other minerals such as:
Related to datolite-gadolinite group.
External Resources for Further Study
For those looking to dive deeper into the specific mineralogical data of
STILLWELLITE-(Ce), we recommend checking high-authority databases:
Final Thoughts
STILLWELLITE-(Ce) is more than just a name on a list; it is a testament to the orderly and beautiful laws of nature. With a chemical backbone of
CeB[SiO4]O and a structure defined by the
Hexagonal-Trigonal system, it holds a specific and important place in the study of mineralogy.We hope this overview has helped clarify the essential data points for this specimen. Whether for academic study or personal interest, understanding these properties brings us one step closer to understanding the Earth itself.
