If you are fascinated by the hidden structures of our planet, you have likely come across
PERRAULTITE. 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
PERRAULTITE. 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,
PERRAULTITE is defined by the chemical formula
BaNaMn2+4Ti2[Si2O7]2O2(OH)2F.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.
PERRAULTITE crystallizes in the
Triclinic 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
Pinacoidal.
- Point Group: 1
- Space Group: C1
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
PERRAULTITE, the dimensions of this microscopic building block are:
a=10.741Å, b=13.841Å, c=11.079Å, α=108.174o, ß=99.186o, γ=89.99o, Z=
The internal arrangement of these atoms is described as:
Sorosilicates: SiO4 tetrahedras combined mainly in pairs, also in larger combos which form isolated grp; Si2 O7 grp w/o non-tetrahedral anions, cations in octahedral [6] &/or other coordination; brucite-like sheets of edge-sharing (Mn,Fe)[6] octahedra // (001) sandwiched btw sheets of Si2O7 grp & Ti[6] octahedra to form 3-layer slabs // (001) linked by large cations, (OH) ions, & shared corners of Ti[6] octahedra.2 See “Additional Structures” tab for entry(s).3-14 TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral); in O sheet, ideal composition of 5 [6]MO sites is Fe2+4apfu (jinshajiangite), Mn4apfu(surkobite), & (Mn7Na) (bobshannonite); there is no order of Fe2+ & Mn in O sheet; in H sheet ideal composition of 2 [6]MH sites is Ti2apfu (jinshajiangite, surkobite) & Nb4apfu (bobshannonite); 4 [4]Si sites are occupied soley by Si; MH octahedra & Si2O7 grp constitute H sheet; TS blocks link via common vertices of MH octahedra; I block contains AP(1.2) & BP(1,2) cation sites; in I block of jinshajiangite & surkobite AP(1) site is occupied by Ba & AP(2) by K > Ba; ideal composition of 2 AP(1,2) sites is Ba apfu; in I block of bobshannonite Ba & K are order at AP(1) & AP(2) sites, Ba:K ~ 1:1, ideally BaK apfu; 2 BP(1,2) sites are each occupied by Na > Ca, ideally Na apfu (jinsha-jiangite, surkobite) & solely by Na, ideally Na2apfu (bonshannonite); there is no order of Na & Ca at BP(1,2) sites in jinshajiangite & surkobite [currently defined as Ca-ordered analog of perraultite, ideally NaBaMn4Ti2 (Si2O7)2O2(OH)2F, Z = 4]. There is 1 type of TS block & 1 type of I block; they alternate along c; TS block consists of HOH sheets; in O sheet ideal composition of 5[6]MO sites is Mn4apfu; there is no order of Mn & Fe2+ in O sheet; MH octahedra & Si2O7 grp constitute H sheet; ideal composition of 2 [6]MH sites is Ti2apfu; TS block link via common vertices of MH octahedra.16This 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
PERRAULTITE in the field, what does it actually look like? A mineral’s “habit” describes its typical shape and growth pattern.
- Common Habit: Prismatic micro crystals, flattened
- Twinning: Simple contact twins, with {001} as twin-composition plane, common
Twinning is a fascinating phenomenon where two or more crystals grow interlocked in a specific symmetrical pattern. If PERRAULTITE 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 pegmatite dikes in nepheline syenite in intrusive alkalic gabbro-syenite complexKnowing 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.
PERRAULTITE is often related to other species, either through similar chemistry or structure.
Relationship Data:
Bafertisite group; Mn – analog of jinshajiangiteUnderstanding 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 PERRAULTITE?The standard chemical formula for PERRAULTITE is
BaNaMn2+4Ti2[Si2O7]2O2(OH)2F. This defines its elemental composition.
2. Which crystal system does PERRAULTITE belong to?PERRAULTITE crystallizes in the
Triclinic system. Its internal symmetry is further classified under the Pinacoidal class.
3. How is PERRAULTITE typically found in nature?The “habit” or typical appearance of PERRAULTITE is described as
Prismatic micro crystals, flattened. This refers to the shape the crystals take when they grow without obstruction.
4. In what geological environments does PERRAULTITE form?PERRAULTITE is typically found in environments described as:
In pegmatite dikes in nepheline syenite in intrusive alkalic gabbro-syenite complex. This gives clues to the geological history of the area where it is discovered.
5. Are there other minerals related to PERRAULTITE?Yes, it is often associated with or related to other minerals such as:
Bafertisite group; Mn – analog of jinshajiangite.
External Resources for Further Study
For those looking to dive deeper into the specific mineralogical data of
PERRAULTITE, we recommend checking high-authority databases:
Final Thoughts
PERRAULTITE 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
BaNaMn2+4Ti2[Si2O7]2O2(OH)2F and a structure defined by the
Triclinic 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.
