WINDHOEKITE Mineral Details

Complete mineralogical data for WINDHOEKITE. Chemical Formula: Ca2Fe3+2.67[Si4O10]2(OH)4(H2O)4·6H2O. Crystal System: Monoclinic. Learn about its geologic occurrence, habit, and identification.

WINDHOEKITE

Ca2Fe3+2.67[Si4O10]2(OH)4(H2O)4·6H2O

Crystal System

Monoclinic

Crystal Class

Prismatic

Space Group

C2/m

Point Group

2/m

Structure & Data

Crystal Structure

Windhoekite & tuperssuatsiaite structures, small octahedral sites (M1 & M2) are predominantly occupied by Fe3+ while large octahedron M3 is occupied by Na in tuperssuatsiaite and Ca in windhoekite; xl structure of windhoekite bears add’l octahedral site (M4) partially occupied by Ca2+ & missing in structure of tuperssuatsiaite; occurrence of this new site indicates high flexibility of palygorskite-like structures toward introduction of even quite large cations; both sites occupied by Ca (M3 & M4) are partially coordinated by H2O molecules & (OH) grp loc in channels of structure; displacement parameters for OW3 could not be refined anisotropically, & so OW3 was refined isotropically; note that similarly large displacement parameters have been found by Cámara et al (2002) for intrachannel H2O in tuperssuatsiaite; while OW3 represents intrachannel molecular H2O, defect nature of OW2 & OW1 sites “incrustating” walls of structural channels equally allows existence of H2O molecules as well as OH- grp; low occupancies of these sites suggest that any bond—valence calculations related to these O atoms are of little applicability in terms of chemical formula calculations; difficulties & consequent uncertainties in refining occupancies of OW1, OW2 & OW3 are reasons for inconsistency of total amt of H2O determined by chemical methods & H2O found during structure refinement.

Cell Data

a=14.319Å, b=17.825Å, c=5.242Å, ß=103.5o, Z=2

Geology & Identification

Geologic Occurrence

From a phonoliteWINDHOEKITEWINDHOEKITE

Habit

Isolated long prismatic micro crystals; radial aggregates

Twinning

Relationships

RELATIONSHIP TO OTHER MINERALS

Palygorskite group

If you are fascinated by the hidden structures of our planet, you have likely come across WINDHOEKITE. 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 WINDHOEKITE. 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, WINDHOEKITE is defined by the chemical formula Ca2Fe3+2.67[Si4O10]2(OH)4(H2O)4·6H2O.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. WINDHOEKITE 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 Prismatic.
  • Point Group: 2/m
  • Space Group: C2/m
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 WINDHOEKITE, the dimensions of this microscopic building block are:
a=14.319Å, b=17.825Å, c=5.242Å, ß=103.5o, Z=2
The internal arrangement of these atoms is described as:Windhoekite & tuperssuatsiaite structures, small octahedral sites (M1 & M2) are predominantly occupied by Fe3+ while large octahedron M3 is occupied by Na in tuperssuatsiaite and Ca in windhoekite; xl structure of windhoekite bears add’l octahedral site (M4) partially occupied by Ca2+ & missing in structure of tuperssuatsiaite; occurrence of this new site indicates high flexibility of palygorskite-like structures toward introduction of even quite large cations; both sites occupied by Ca (M3 & M4) are partially coordinated by H2O molecules & (OH) grp loc in channels of structure; displacement parameters for OW3 could not be refined anisotropically, & so OW3 was refined isotropically; note that similarly large displacement parameters have been found by Cámara et al (2002) for intrachannel H2O in tuperssuatsiaite; while OW3 represents intrachannel molecular H2O, defect nature of OW2 & OW1 sites “incrustating” walls of structural channels equally allows existence of H2O molecules as well as OH- grp; low occupancies of these sites suggest that any bond—valence calculations related to these O atoms are of little applicability in terms of chemical formula calculations; difficulties & consequent uncertainties in refining occupancies of OW1, OW2 & OW3 are reasons for inconsistency of total amt of H2O determined by chemical methods & H2O found during structure refinement.This 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 WINDHOEKITE in the field, what does it actually look like? A mineral’s “habit” describes its typical shape and growth pattern.
  • Common Habit: Isolated long prismatic micro crystals; radial aggregates
  • Twinning: 
Twinning is a fascinating phenomenon where two or more crystals grow interlocked in a specific symmetrical pattern. If WINDHOEKITE 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: From a phonoliteKnowing 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. WINDHOEKITE is often related to other species, either through similar chemistry or structure.Relationship Data: Palygorskite 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 WINDHOEKITE?The standard chemical formula for WINDHOEKITE is Ca2Fe3+2.67[Si4O10]2(OH)4(H2O)4·6H2O. This defines its elemental composition.
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2. Which crystal system does WINDHOEKITE belong to?WINDHOEKITE crystallizes in the Monoclinic system. Its internal symmetry is further classified under the Prismatic class.3. How is WINDHOEKITE typically found in nature?The “habit” or typical appearance of WINDHOEKITE is described as Isolated long prismatic micro crystals; radial aggregates. This refers to the shape the crystals take when they grow without obstruction.4. In what geological environments does WINDHOEKITE form?WINDHOEKITE is typically found in environments described as: From a phonolite. This gives clues to the geological history of the area where it is discovered.5. Are there other minerals related to WINDHOEKITE?Yes, it is often associated with or related to other minerals such as: Palygorskite group.

External Resources for Further Study

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

Final Thoughts

WINDHOEKITE 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 Ca2Fe3+2.67[Si4O10]2(OH)4(H2O)4·6H2O 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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