FRANKLINFURNACEITE Mineral Details

Complete mineralogical data for FRANKLINFURNACEITE. Chemical Formula: Ca2Mn2+3Mn3+Fe3+[Zn2Si2O10](OH)8. Crystal System: Monoclinic. Learn about its geologic occurrence, habit, and identification.

FRANKLINFURNACEITE

Ca2Mn2+3Mn3+Fe3+[Zn2Si2O10](OH)8

Crystal System

Monoclinic

Crystal Class

Sphenoidal

Space Group

C2

Point Group

2

Structure & Data

Crystal Structure

Phyllosilicates: rings of tetrahedra are linked into continuous sheets; single nets of tetrahedra; mica-like tetrahedral-octahedral-tetrahedral (2:1) layers alternate with gibbsite- or brucite-type interlayers.2 Structure is derivative of structure of chlorite via substitution of Ca in sites that are ordinarily unoccupied btw 2:1 layers & octahedral interlayers: (1) type IIa structure (IIa-1), (2) tri-dioctahedral chlorite, (3) structure with Ca occupying octahedral sites btw tetrahedral sheets & octahedral interlayers; being intermediate btw those of brittle micas & chlorite, in that it has both interlayer cations & octahedral interlayer; alternating Zn & Si are ordered in tetrahedral sheets; octahedral sheet of 2:1 layer is trioctahedral with ordered Mn3+ & divalent cations; interlayer dioctahedral sheet has ordered divalent cations Mn3+, Fe3+ & vacancies, & it has net (-) charge; optimum local charge balance is maintained by sandwiching of interlayer octahedral vacancies btw opposing Ca sites, Mn2+ btw Si4+ atoms, & Fe3+ btw 2 Zn2+ atoms; large tetrahedral Zn permits large terahedral rotation angle, a of 23.5o, thereby allowing anions to form nearly ideal, 3-D closest-packing sequence …CABABC…; consequently, octahedrally coordinated site suitable for Ca is formed, & IIa structure results; Ca repels H protons so that there is no interlayer H— bonding system.3 See “Additional Structures” tab for entry(s).4a,4b,4c

Cell Data

a=5.48Å, b=9.39Å, c=14.51Å, ß=97.0o, Z=2

Geology & Identification

Geologic Occurrence

Dissemenated in hematite ore; an authigenic mineral in aeolian sandstones; in low-grade metamorphic assemblagesFRANKLINFURNACEITEFRANKLINFURNACEITE

Habit

Fine-grained

Twinning

Relationships

RELATIONSHIP TO OTHER MINERALS

Chlorite group

If you are fascinated by the hidden structures of our planet, you have likely come across FRANKLINFURNACEITE. 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 FRANKLINFURNACEITE. 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, FRANKLINFURNACEITE is defined by the chemical formula Ca2Mn2+3Mn3+Fe3+[Zn2Si2O10](OH)8.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. FRANKLINFURNACEITE crystallizes in the Monoclinic 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 Sphenoidal.
  • Point Group: 2
  • Space Group: C2
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.
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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 FRANKLINFURNACEITE, the dimensions of this microscopic building block are:
a=5.48Å, b=9.39Å, c=14.51Å, ß=97.0o, Z=2
The internal arrangement of these atoms is described as:Phyllosilicates: rings of tetrahedra are linked into continuous sheets; single nets of tetrahedra; mica-like tetrahedral-octahedral-tetrahedral (2:1) layers alternate with gibbsite- or brucite-type interlayers.2 Structure is derivative of structure of chlorite via substitution of Ca in sites that are ordinarily unoccupied btw 2:1 layers & octahedral interlayers: (1) type IIa structure (IIa-1), (2) tri-dioctahedral chlorite, (3) structure with Ca occupying octahedral sites btw tetrahedral sheets & octahedral interlayers; being intermediate btw those of brittle micas & chlorite, in that it has both interlayer cations & octahedral interlayer; alternating Zn & Si are ordered in tetrahedral sheets; octahedral sheet of 2:1 layer is trioctahedral with ordered Mn3+ & divalent cations; interlayer dioctahedral sheet has ordered divalent cations Mn3+, Fe3+ & vacancies, & it has net (-) charge; optimum local charge balance is maintained by sandwiching of interlayer octahedral vacancies btw opposing Ca sites, Mn2+ btw Si4+ atoms, & Fe3+ btw 2 Zn2+ atoms; large tetrahedral Zn permits large terahedral rotation angle, a of 23.5o, thereby allowing anions to form nearly ideal, 3-D closest-packing sequence …CABABC…; consequently, octahedrally coordinated site suitable for Ca is formed, & IIa structure results; Ca repels H protons so that there is no interlayer H— bonding system.3 See “Additional Structures” tab for entry(s).4a,4b,4cThis internal structure is the invisible framework that supports everything we see on the outside, from the mineral’s density to its hardness.
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Physical Appearance (Habit)

When you find FRANKLINFURNACEITE in the field, what does it actually look like? A mineral’s “habit” describes its typical shape and growth pattern.
  • Common Habit: Fine-grained
  • Twinning: 
Twinning is a fascinating phenomenon where two or more crystals grow interlocked in a specific symmetrical pattern. If FRANKLINFURNACEITE 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: Dissemenated in hematite ore; an authigenic mineral in aeolian sandstones; in low-grade metamorphic assemblagesKnowing 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. FRANKLINFURNACEITE is often related to other species, either through similar chemistry or structure.Relationship Data: Chlorite 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 FRANKLINFURNACEITE?The standard chemical formula for FRANKLINFURNACEITE is Ca2Mn2+3Mn3+Fe3+[Zn2Si2O10](OH)8. This defines its elemental composition.
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2. Which crystal system does FRANKLINFURNACEITE belong to?FRANKLINFURNACEITE crystallizes in the Monoclinic system. Its internal symmetry is further classified under the Sphenoidal class.3. How is FRANKLINFURNACEITE typically found in nature?The “habit” or typical appearance of FRANKLINFURNACEITE is described as Fine-grained. This refers to the shape the crystals take when they grow without obstruction.4. In what geological environments does FRANKLINFURNACEITE form?FRANKLINFURNACEITE is typically found in environments described as: Dissemenated in hematite ore; an authigenic mineral in aeolian sandstones; in low-grade metamorphic assemblages. This gives clues to the geological history of the area where it is discovered.5. Are there other minerals related to FRANKLINFURNACEITE?Yes, it is often associated with or related to other minerals such as: Chlorite group.

External Resources for Further Study

For those looking to dive deeper into the specific mineralogical data of FRANKLINFURNACEITE, we recommend checking high-authority databases:

Final Thoughts

FRANKLINFURNACEITE 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 Ca2Mn2+3Mn3+Fe3+[Zn2Si2O10](OH)8 and a structure defined by the Monoclinic 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.
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