25 Facts About Althausite

Discovery and Naming

Althausite is a rare mineral with a fascinating backstory. Let's dive into its origins and the person behind its name.

1. Discovery and Naming
   Althausite was first identified in the 1970s. It was named after Professor Egon Althaus, a renowned mineralogist from the University of Karlsruhe, Germany. His contributions to mineralogy were significant, and this mineral honors his legacy.

Chemical Composition and Structure

Understanding the chemical makeup and structure of althausite helps in appreciating its unique properties.

2. Chemical Composition
   The chemical formula for althausite is Mg₂(PO₄)(OH,F). This means it contains magnesium, phosphate, hydroxide, and fluoride ions. Its molecular weight is about 161.09 grams per mole.

3. Crystal Structure
   Althausite crystallizes in the orthorhombic crystal system. This system is characterized by a dipyramidal crystal class (mmm) and a space group of Pnma. This structure gives althausite its distinct physical properties.

Physical Properties

The physical attributes of althausite make it stand out among other minerals.

4. Color
   Typically, althausite appears gray in color.

5. Luster
   It has a vitreous, or glassy, luster.

6. Streak
   When scratched on a porcelain plate, althausite leaves a white streak.

7. Hardness
   On the Mohs scale, althausite has a hardness of 3.5, making it relatively soft.

Occurrence and Rarity

Where althausite is found and its rarity add to its intrigue.

8. Occurrence
   Althausite is found in serpentine-magnesite deposits, mainly in Norway and Portugal. The type locality is the Tingelstadtjern and Overntjern quarries in Modum, Buskerud, Norway. It is also present in the Panasqueira Sn-W deposit in Portugal.

9. Rarity
   This mineral is considered rare due to the specific geological conditions required for its formation. The presence of magnesium and phosphate ions in serpentine-magnesite deposits is crucial.

Mineralogical Association and Classification

Althausite's classification helps in understanding its place among other minerals.

10. Mineralogical Association
    Althausite is classified as a phosphate mineral under the International Mineralogical Association (IMA) classification. It belongs to the Strunz classification group 8.BB.25, which includes other magnesium phosphate minerals.

Thermal and High-Pressure Properties

Althausite's behavior under different conditions reveals much about its potential applications.

11. Thermal Expansion and Compressibility
    Studies show that althausite has higher thermal-expansion coefficients compared to homeotypical silicates. Its unit-cell parameters change significantly under high pressure, although detailed refinement above 3.2 GPa is challenging due to strong orientation effects along its (001) perfect cleavage.

12. High-Pressure Behavior
    Experimental methods reveal that althausite's volume changes significantly under compressive forces. This indicates potential use in high-pressure applications, although precise compressibility measurements are hindered by limited diffraction pattern peaks.

Synthetic Varieties and Optical Properties

Synthetic studies and optical characteristics provide deeper insights into althausite.

13. Synthetic Varieties
    Synthetic magnesium phosphates, including althausite, have been extensively studied. These synthetic forms help understand the structural and optical properties of natural althausite.

14. Optical Properties
    Althausite's orthorhombic crystal structure influences its optical properties. The dipyramidal crystal class affects its refractive indices and optical behavior, essential for accurate mineral identification.

Identification and Environmental Conditions

Identifying althausite and understanding its formation environment are key for mineralogists.

15. Identification
    Identifying althausite requires examining its physical and chemical properties. The presence of magnesium, phosphate, hydroxide, and fluoride ions is crucial. X-ray diffraction patterns confirm its orthorhombic crystal structure.

16. Environmental Conditions
    Althausite forms in specific conditions, typically in serpentine-magnesite deposits. These deposits provide the necessary magnesium and phosphate ions, with hydroxide and fluoride ions contributing to its unique composition.

Geological Significance and Collection

The geological importance and collectibility of althausite add to its value.

17. Geological Significance
    Understanding althausite's geological significance aids in mineral exploration and mapping. Its occurrence in specific deposits provides valuable information about the geological history of those regions.

18. Mineral Collection
    Althausite is prized among collectors due to its rarity and unique composition. However, its softness and limited availability make it challenging to collect and preserve.

Educational and Research Applications

Althausite's unique properties make it valuable in education and research.

19. Educational Value
    Althausite serves as an excellent teaching tool in mineralogy classes. Its unique properties and rare occurrence make it an engaging subject for students.

20. Research Applications
    The study of althausite has various research applications. Its high-pressure behavior and thermal expansion properties make it a subject of interest in materials science and geophysics.

Historical Context and Classification

The history and classification of althausite provide context for its study.

21. Historical Context
    The discovery and naming of althausite reflect the historical context of mineralogy. Recognizing Professor Egon Althaus's contributions highlights the importance of individual researchers.

22. Classification
    Althausite is classified under the phosphate minerals category. Its specific classification within this group is 8.BB.25 according to the Strunz classification system.

Crystal Dimensions and Cleavage

Detailed crystal dimensions and cleavage properties are essential for understanding althausite.

23. Crystal Dimensions
    The crystal dimensions of althausite are a = 8.258 Å, b = 14.383 Å, and c = 6.054 Å. The unit cell volume is approximately 719.06 ų, and the calculated density is 2.98 g/cm³.

24. Cleavage
    Althausite exhibits perfect cleavage along one plane, a characteristic feature of its orthorhombic crystal structure. This cleavage plane is significant for its physical properties and identification.

Type Locality and Future Research

The type locality and future research directions offer more avenues for exploration.

25. Type Locality
    The type locality for althausite is the Tingelstadtjern and Overntjern quarries in Modum, Buskerud, Norway. This location is significant for mineralogical studies and collections.

Future research on althausite could focus on its high-pressure behavior, thermal expansion properties, and potential applications in materials science. Studying its occurrence in different geological settings can provide insights into the formation processes of phosphate minerals in various environments.

The Fascinating World of Althausite

Althausite, with its unique composition and rare occurrence, stands out in the mineral world. Named after Professor Egon Althaus, this magnesium phosphate mineral boasts a chemical formula of Mg₂(PO₄)(OH,F) and crystallizes in the orthorhombic system. Found primarily in Norway and Portugal, it forms in serpentine-magnesite deposits. Its gray color, vitreous luster, and white streak make it identifiable, though its hardness of 3.5 on the Mohs scale means it's relatively soft.

Althausite's high-pressure behavior and thermal expansion properties offer intriguing research opportunities. Its perfect cleavage and specific crystal dimensions further add to its distinctiveness. While rare, it holds significant educational value and is a prized find for mineral collectors. Future studies could unlock even more about this fascinating mineral, contributing to advancements in materials science and geophysics. Althausite truly is a gem in the world of mineralogy.