If you are fascinated by the hidden structures of our planet, you have likely come across
GUILLEMINITE. 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
GUILLEMINITE. 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,
GUILLEMINITE is defined by the chemical formula
Ba(UO2)3(Se4+O3)2O2(H2O)4.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.
GUILLEMINITE crystallizes in the
Orthorhombic 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
Pyramidal.
- Point Group: m m 2
- Space Group: P21nm
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
GUILLEMINITE, the dimensions of this microscopic building block are:
a=7.08Å, b=7.29Å, c=16.88Å, Z=2
The internal arrangement of these atoms is described as:
Cation coordinations varying from [2] to [10] & polyhedra linked in var ways; selenites w/o add’l anions with H2O edge-sharing dimers of UO7 polyhedra share edges with UO8 polyhedra to form chains // [100]; chains connected by SeO3 trig ∆ to form sheets // (010); sheets linked by Ba[10] atoms & H—bonding from interstitial H2O molecules.1 There is 1 unique Ba atom, coordinated by [7] O atoms & [3] H2O grp in capped tri-augumented trig prismatic array; there is 1 unique Se atom coordinated by [3] O atoms, & these [4] atoms form a triangular ∆ with Si in apical position, characteristic of stereoactive lone-pair behavior; there are 2 distinct U atoms: U(1) is coordinated by a hexagonal bi-∆ array of O atoms, & U(2) is coordinated by pentagonal bi-∆ array of O atoms; in both polyhedra, apical O atoms constitute uranyl O atoms; (UO7) grp form edge-sharing dimers that are linked into chains of form [U3O14] by sharing edges with (UO8) monomers; chains extend along [100] & are cross-linked in [001] direction by (SeO3) grp to form sheets of form [U3(Se O3)2O8] || to (010); sheets are topologically identical to sheets in phosphyranylite except for (SeO3) grp proxy for (PO4) grp.2 Refinement of xl structure allowed determination of add’l site arranged within void of interlayer space & occupied by H2O molecule.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
GUILLEMINITE in the field, what does it actually look like? A mineral’s “habit” describes its typical shape and growth pattern.
- Common Habit: As rectangular micro crystals, tabular; as coatings and silky masses
- Twinning:
Twinning is a fascinating phenomenon where two or more crystals grow interlocked in a specific symmetrical pattern. If GUILLEMINITE 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:
In oxidized portions of Cu-Co sulfide depositKnowing 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.
GUILLEMINITE is often related to other species, either through similar chemistry or structure.
Relationship Data:
Compare haynesite, larisaite, piretiteUnderstanding 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 GUILLEMINITE?The standard chemical formula for GUILLEMINITE is
Ba(UO2)3(Se4+O3)2O2(H2O)4. This defines its elemental composition.
2. Which crystal system does GUILLEMINITE belong to?GUILLEMINITE crystallizes in the
Orthorhombic system. Its internal symmetry is further classified under the Pyramidal class.
3. How is GUILLEMINITE typically found in nature?The “habit” or typical appearance of GUILLEMINITE is described as
As rectangular micro crystals, tabular; as coatings and silky masses. This refers to the shape the crystals take when they grow without obstruction.
4. In what geological environments does GUILLEMINITE form?GUILLEMINITE is typically found in environments described as:
In oxidized portions of Cu-Co sulfide deposit. This gives clues to the geological history of the area where it is discovered.
5. Are there other minerals related to GUILLEMINITE?Yes, it is often associated with or related to other minerals such as:
Compare haynesite, larisaite, piretite.
External Resources for Further Study
For those looking to dive deeper into the specific mineralogical data of
GUILLEMINITE, we recommend checking high-authority databases:
Final Thoughts
GUILLEMINITE 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
Ba(UO2)3(Se4+O3)2O2(H2O)4 and a structure defined by the
Orthorhombic 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.
