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Selenite, gypsum, satin spar, and desert rose stand out for their unique appearance and crystal healing properties.

While often lumped together or confused due to their similarities, each of these minerals has distinct characteristics that set it apart. 

Let's dive in and explore their differences and shed light on their individual aspects.

Gypsum: The Mother Mineral

At the heart of these four minerals is gypsum, a soft sulfate mineral composed of calcium sulfate dihydrate. Gypsum is known for its versatility and is a key ingredient in plaster, blackboard chalk, and wallboard products.  

It's the foundational mineral from which selenite, satin spar, and desert rose are formed, showcasing the incredible diversity that can arise from a single mineral base.

This mineral can be transparent to opaque, and its crystals can form in a variety of shapes and sizes, from the massive, fibrous to the delicately crystalline.

There is another variety of gypsum that we won't discuss here, the fine-grain variety called alabaster. Alabaster is a soft rock commonly used for carvings.



What is Selenite? The Transparent Beauty

Selenite, a variety of gypsum, has a transparent, glass-like appearance. Its name, derived from the Greek word 'Selene' for the moon, alludes to its soft, ethereal glow reminiscent of moonlight. 

Selenite crystals are typically found in large, tabular form, showcasing clarity and a pearl-like lustre that ranges from transparent to translucent. 

Selenite is prized among collectors and practitioners of crystal healing for its metaphysical properties, including clarity of mind, peace, and protection. 


What is Satin Spar? The Fibrous Twin

Satin spar, another variety of gypsum, has a fibrous, silky lustre that gives it a satin-like appearance. This variety typically forms in compact, fibrous masses that exhibit a chatoyant, or 'cat's eye', optical effect. Its fibrous strands reflect light in a way that resembles the sheen of satin fabric. 

Often mistaken for selenite due to their visual similarities and shared mineral composition, satin spar differs in its internal structure and the way it refracts light. It is commonly used in ornamental carvings, lamps, bowls, and jewellery.


What is Desert Rose? 

Desert rose is a gypsum variety that forms rosette-like structures composed of interlocking crystal plates. This variety gets its name for its resemblance to rose petals, with its clusters often mimicking the form of a blooming flower. 

Desert roses are typically found in arid, sandy environments, where the conditions are just right for their unique formation.

The intricate patterns and earth-toned colours of desert rose make it a collector's favourite. Its presence symbolises the heart's strength and the beauty of the natural world, making it a cherished item in various cultural and metaphysical contexts.


What is the Chemical Composition of Gypsum, Selenite, Satin Spar and Desert Rose?

The chemical composition of selenite, gypsum, satin spar, and desert rose is fundamentally the same, as they are all varieties of the mineral gypsum. 

The chemical formula for gypsum is: CaSO₄⋅2H2OCaSO₄​⋅2H2₂O

This formula represents calcium sulfate dihydrate, comprising calcium (Ca), sulphur (S), oxygen (O), and water (H₂O). The "2H₂O" part of the formula indicates that there are two molecules of water for every molecule of calcium sulfate. This characteristic contributes to gypsum's softness and ability to form in various shapes and textures.

When gypsum is heated, part of its water content is removed. This process creates calcium sulfate hemihydrate - the main component of Plaster of Paris. 

Despite their identical chemical compositions, the differences in appearance and physical properties among selenite, satin spar, and desert rose are due to variations in their crystal formation processes, including conditions like temperature and pressure and the presence of other minerals or organic matter that can affect their textures, forms, and colours.  

This diversity showcases the remarkable ways the same chemical building blocks can manifest in nature.


Why Does Satin Spar, Selenite and Desert Rose have Different Shapes?

Selenite, gypsum, satin spar, and desert rose, all variations of the mineral gypsum, belong to the monoclinic crystal system. In this system, crystals typically have three axes of unequal length. Two of the axes are inclined towards each other at an oblique angle (an angle which is not a multiple of 90°). The third is perpendicular (at 90°) to the plane formed by the first two.

The monoclinic crystal system allows for a wide variety of crystal shapes, contributing to the diverse appearances of gypsum's different forms. Despite their different appearances:

  • Selenite crystals often form in elongated, transparent, tabular shapes that can exhibit a pearly lustre.
  • Satin Spar gypsum manifests as fibrous or silky, often displaying a satin-like sheen due to its finely fibrous structure.
  • Desert Rose forms rosette-like structures made up of gypsum crystals grouping together, resembling the petals of a rose.

The internal crystal structure and the conditions under which each form crystallises contribute to their unique textures, shapes, and appearances, all within the framework of the monoclinic system. 

This system's versatility in crystal growth directions and angles helps explain the variety of forms that gypsum can take while maintaining the same basic chemical composition.


What About Ram’s Horn and Gypsum Flowers?

“Ram’s horn” describes a specific shape or form of satin spar. This form is characterised by long, fibrous crystals that can wind and twist as they grow, mimicking the shape of a ram’s horn.

Gypsum flowers, on the other hand, are another form of gypsum that are most often acicular, scaly, stellate, and lenticular. However, they can also form “ram’s horns”, “fishtail”, “arrow/spearhead”, and “swallowtail” twins.

So, while “ram’s horn” is a specific form of satin spar gypsum, it can also be a type of gypsum flower. However, not all gypsum flowers are “ram’s horns”. The terms refer to different aspects of the mineral’s crystal habit or shape. 

In Conclusion

While selenite, satin spar, and desert rose are all manifestations of the mineral gypsum, they differ in appearance and shape.

Each presents a unique form, from the moonlit glow of selenite to the delicate petals of desert rose; these minerals remind us of nature's ability to create beauty in diversity. Exploring the differences and similarities among these minerals offers a journey into the heart of the Earth's creative essence.

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