When limestone undergoes metamorphism and transforms into marble, several changes occur. This process is known as metamorphism, and it involves recrystallization of the original minerals in the limestone. Here’s what happens:

1. Recrystallization: The calcite crystals in limestone are typically small and randomly oriented. During metamorphism, these crystals recrystallize, growing larger and developing a more uniform and interlocking texture.

2. Mineral Change: The main mineral in limestone is calcite (calcium carbonate). Through metamorphism, calcite recrystallizes into larger crystals of calcite or, in some cases, can even be transformed into other minerals like dolomite.

3. Texture: The texture of limestone is often granular, but in marble, it becomes more crystalline and can exhibit a variety of patterns, including veining and color variations.

4. Hardness: Marble is generally harder than limestone due to the recrystallization process, which results in a denser and more tightly packed structure.

5. Color Changes: While limestone is often light-colored, marble can exhibit a broader range of colors depending on the impurities present during metamorphism. These impurities may introduce shades of gray, green, pink, or other hues.

6. Loss of Fossils: Limestone often contains fossils, but these are typically lost during the metamorphic process as the original structure is obliterated.

Marble is prized for its aesthetic qualities and is commonly used in sculpture and as a building material for flooring and countertops due to its durability and attractive appearance.

Pyrite is a type of iron sulfide mineral that forms in a variety of geometric shapes due to its unique crystallographic properties. The formation of pyrite can be attributed to the following factors:

1. Crystal growth: Pyrite typically forms through a process called crystal growth, where individual crystals grow from a solution of iron sulfide. This process leads to the formation of a well-ordered, geometric structure.

2. Crystal lattice: Pyrite has a face-centered cubic (FCC) crystal lattice, which is a type of close-packed lattice structure. This arrangement of atoms in the lattice creates a highly ordered, geometric structure.

3. Depositional environment: Pyrite often forms in depositional environments where the iron sulfide solution is in equilibrium with other miner 4. Depositional factors, such as temperature, pressure, and the presence of water, can influence the growth of pyrite crystals and result in their unique geometrical shapes.

4. Microcrystalline aggregates: Pyrite can also form as microcrystalline aggregates, which are groups of small, uniformly sized crystals that are closely packed together. This formation process can result in the formation of geometrical shapes such as dendritic, fibrous, or massive pyrite.

In summary, the formation of pyrite is geometrical due to the unique properties of its crystal lattice, the process of crystal growth, and the depositional factors that influence its formation.