The main types of sedimentary rocks are clastic or chemical. Some sedimentary rocks are a third type, organic….Some Common Sedimentary Rocks.

Clastic sedimentary rocks form from the accumulation and lithification of mechanical weathering debris. Examples include: breccia, conglomerate, sandstone, siltstone, and shale. Examples include: chert, some dolomites, flint, iron ore, limestones, and rock salt.

Shale, any of a group of fine-grained, laminated sedimentary rocks consisting of silt- and clay-sized particles. Shale is the most abundant of the sedimentary rocks, accounting for roughly 70 percent of this rock type in the crust of the Earth.

Sedimentary rocks are largely found on the Earth’s surface. They cover 75% area of the Earth. These rocks are generally not crystalline in nature. They are soft and have many layers as they are formed due to the deposition of sediments.

Cross-bedding is most common is sandstones.

• Feature # 3. Ripple Marks:
• Feature # 4. Rill Marks:
• Feature # 5. Rain Prints:
• Feature # 6. Mud Cracks and Mud Curls:
• Feature # 7. Fossils:
• Feature # 9. Concretions:
• Feature # 10. Stylolites:
• Feature # 11. Colour of Sedimentary Rocks:

They are important for: Earth history. Sedimentary rocks contain features that allow us to interpret ancient depositional environments, including the evolution of organisms and the environments they lived in, how climate has changed throughout Earth history, where and when faults were active, etc. Economic resources.

The most abundant detrital minerals in sediments are quartz and clays. Quartz is an abundant mineral in many rocks. It resists cracking and mechanical weathering and is resistant to solution and decomposition from chemical weathering.

Shale is a fine-grained laminated sedimentary rock composed of silt and clay-sized particles.

Sedimentary rocks are economically important in that they can easily be used as construction material because they are soft and easy to cut. Sedimentary rocks often form porous and permeable reservoirs in sedimentary basins in which water and important minerals such as oil can be found.

• Oil, natural gas, coal, and uranium, our major energy resources, are formed in and come from sedimentary rocks.
• Sand and gravel for construction come from sediment.
• Sandstone and limestone are used for building stone.
• Rock gypsum is used to make plaster.
• Limestone is used to make cement.
• Salt is used for flavoring.

There are two main types of metamorphic rocks: those that are foliated because they have formed in an environment with either directed pressure or shear stress, and those that are not foliated because they have formed in an environment without directed pressure or relatively near the surface with very little pressure …

High-grade metamorphism takes place at temperatures greater than 320oC and relatively high pressure….Some terms that describe this general bulk chemical composition are as follows:

• Pelitic.
• Quartzo-Feldspathic.
• Calcareous.
• Basic.
• Magnesian.
• Ferriginous.
• Manganiferrous.

Can you identify my rock or mineral?

1. Your state geological survey.
2. A natural science museum.
3. A college or university with a geology department.
4. A rockshop.
5. Members of a local Gem & Mineral club or Rockhunting club (many hobbyists are experts at identification)
6. Vendors at a Gem & Mineral show.

Hiking through the woods or strolling along the beach, you may see an unusual rock, and – if it’s your lucky day – the rock may be valuable. To determine if it has monetary value, test it for color and hardness, and inspect it for surface markings that may identify it as a meteorite.

Here are some suggestions:

1. Check out the tumble stone sections on my website.
2. Check out crystal books.
3. Ask at your local crystal shop.
4. Ask the experts and enthusiasts at your local lapidary club or gem show.
5. Use a pendulum to ask a crystal what it is.
6. Identifying crystals by colour.

Painite

In fact, high-quality emeralds, rubies, and sapphires are all rarer in nature than diamonds. However, nearly colorless diamonds can top prices of $10,000 per carat because demand for them has been carefully cultivated and supply is tightly controlled.

Emeralds

The World’s Top 10 Rarest and Most Expensive Gemstones

• Musgravite.
• Jadeite.
• Alexandrite.
• Red Beryl.
• Benitoite.
• Black Opal.
• Taaffeite.
• Tanzanite. This striking blueish-purple stone is found exclusively in the Merelani foothills of Mount Kilimanjaro in Tanzania.

Top 15 Most Expensive Gemstones In The World

• Blue Diamond – $3.93 million per carat. Blue diamond.
• Jadeite – $3 million per carat.
• Pink Diamond – $1.19 million per carat.
• Red Diamond – $1,000,000 per carat.
• Emerald – $305,000 per carat.
• Taaffeite – $35,000 per carat.
• Serendibite – $18,000 per carat.
• Diamond – $15,000 per carat.

The rarest of them all is red diamond which is arguably the rarest birthstone. It is estimated that there are about 20 to 30 red diamond specimens known with the most famous being the 5.1 carat Moussaieff Red.

Sapphires are much rarer than diamonds, but not as rare as gem-quality emeralds or rubies. However, there are some types of sapphire that are dramatically rare, such as the orange and pink padparadscha sapphire.