Igneous Rocks

• Rocks are classified into three main types: Igneous, Sedimentary, and Metamorphic.
• The Rock Cycle illustrates how rocks transition between these types through various processes.

Igneous Rocks

• Igneous rocks form from the cooling and solidification of magma or lava
• Magma cools beneath the surface to form intrusive igneous rocks
• Lava cools on the surface to form extrusive igneous rocks
• Intrusive rocks cool over thousands of years, resulting in coarse-grained textures with visible crystal growth.
  • Examples of intrusive rocks include Diorite, Granite, and Pegmatite.
• Extrusive rocks cool quickly in seconds to months. They have fine-grained textures and typically lack crystal growth.
  • Examples of extrusive rocks include Pumice, Basalt, and Andesite.
• Rapid cooling rates lead to fine crystal sizes, while slow cooling rates lead to large crystal sizes.
• Igneous rocks have varying silica content:
  • Felsic rocks have high silica content
  • Mafic ones have low silica content
  • Intermediate rocks fall in between.
• Granite is un-stratified and dense, with an interlocking texture known for strength.
• Granite is non-permeable and rich in silica and minerals, making it resistant to weathering and abrasion.
• The presence of mural joints in granite makes it suitable for quarrying.
• Granite is used for bathroom dados, kitchen countertops, sculptures, flooring, door and window frames, garden benches, and stair floors.
• Granite colors vary and include Green, Pink, Gray, Brown, Porphyritic, and White, depending on mineral composition.

Sedimentary Rocks

• Weathering and erosion break down rocks into sediments
• Sediments are transported and deposited in water bodies
• Compaction and cementation then transform the accumulated sediments into sedimentary rocks.
• Sedimentary rocks are classified as Clastic, Chemical, or Organic.
• Clastic sedimentary rocks form from the compaction of rock fragments (clasts).
  • Examples: Shale, Siltstone, and Sandstone
• Chemical sedimentary rocks form by precipitation of minerals.
  • Examples: Limestone, Coquina and Chert
• Organic sedimentary rocks form from the accumulation of animal or plant debris.
  • Examples: Chalk and coal
• Other sedimentary rocks include Bituminous Coal, Chalk Lumps, Chert, Conglomerate, Diatomite, Flint, Limestone Black, Limestone Silicious, Limestone White, Mud Stone, Rock Phosphate, Rock Salt, Sandstone Red, Sandstone Silicious, and Shale.

Metamorphic Rocks

• Metamorphic rocks form by the effect of heat and pressure on existing rocks.
• This process can change the hardness, texture, or layer patterns.
• Metamorphic rocks are classified as Foliated or Non-Foliated.
  • Foliated examples: Slate, Schist, and Gneiss
  • Non-Foliated examples: Marble, Quartzite, and Hornfels

Marble

• Marble has varying colors like White,Pink, Black, Green, Shaded, and Striped
• Marble has a glassy luster
• Marble's reflectivity ranges from 80-95%
• It is translucent with negligible solubility and absorption.
• Marble contains the following chemical constituents: Soluble residue 0.89%, Fe203 - 0.28%, CaCo3 - 97.74%, MgCo3 - 1.22%, Phosphoric Acid - 0.04%
• Marble has always been highly valued for its beauty, strength, and resistance to fire and erosion.
• The ancient Greeks used it in their buildings and statues.
• Michelangelo used marble from Carrara, Italy, in sculptures.
• Tennessee marble was used in the National Gallery of Art in Washington, D.C.
• The Lincoln Memorial was built of marble from Alabama, Colorado, & Georgia.
• Marble is used for kitchen and bathroom countertops, and wall applications.
• Examples of marble include: Statuary White, Fior De Pesco, Crema Marfil, Cafe Rosita, Verde Rameggiata, and Rose Atlantico.

Grain Size

• The Udden-Wentworth scale is a millimeter-based scale for classifying grain size
• The Phi (φ) scale expresses grain sizes on a logarithmic scale related to grain diameter (d) by the expression φ = -log2d.
• Sizes range from Clay (<0.004 mm, >8 φ) to Boulder (>256 mm, -8 to -12 φ).
• Other classifications include Silt, Very Fine Sand, Fine Sand, Medium Sand, Coarse Sand, Very Coarse Sand, Gravel, and Pebbles.

Igneous rocks form from the cooling and solidification of magma or lava. Intrusive rocks cool slowly beneath the surface, forming coarse-grained textures. Extrusive rocks cool quickly on the surface, resulting in fine-grained textures.