When sediments settle out of calmer water, they form horizontal layers. One layer is deposited first, and another layer is deposited on top of it. When the sediments harden, the layers are preserved. Sedimentary rocks formed by the crystallization of chemical precipitates are called chemical sedimentary rocks.

Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. Sedimentary rocks are also important sources of natural resources including coal, fossil fuels, drinking water and ores.

zircons

diamond

7 billion-year-old stardust is the oldest stuff on Earth. Microscopic grains of dead stars are the oldest known material on the planet — older than the moon, Earth and the solar system itself.

4.375 billion years

zircon crystals

Taaffeite

Most Powerful Crystals

• Clear Quartz. Clear quartz, also called rock crystal, is known as a master healer and a stone of great power.
• Ruby. The ruby is said to be the most powerful gem in the universe because of its high energy.
• Amethyst.
• Malachite.
• Aventurine.
• Citrine.
• Kunzite.

Most Expensive Crystals

1. The Pink Star Diamond – $1,395,761 per carat :
2. Painite – $50,000-60,000 per carat :
3. Musgravite – $35,000 per carat :
4. Jadeite – $20,000 per carat :
5. Alexandrite – $12,000 per carat.
6. Red Beryl – $10,000 per carat.
7. Benitoite – $3000-4000 per carat.
8. Opal – $2355 per carat.

10 Most Popular Crystals

• Celestite.
• Citrine.
• Fluorite.
• Garnets.
• Malachite.
• Pyrite (Fools Gold)
• Rhodochrosite.
• Quartz. A couple variations of quartz, amethyst and citrine already appear on this list, but quartz in general is the most common type of crystal people search for.

Fluorite may be the world’s most colourful mineral, because of the enormous range of brilliant and even iridescent colours it displays. The funny thing is, pure fluorite crystals are transparent.

red diamond

A very high quality natural black diamond is incredibly rare since most carbonado is made up of minuscule, porous crystals. Due to this rarity, a natural gem quality black diamond can be more expensive than a colorless diamond of similar quality.

Blue Diamonds

This month, the ‘Blue Moon’ diamond sold for a whopping $48.4 million, making it the world’s most expensive diamond. Auctioneer David Bennett called it the “highest price per carat” ever obtained for any kind of stone. The record sale, which took place at a Sotheby’s auction in Geneva, was a headline in itself.

green diamonds

Topping our list of the most expensive diamonds in the world is the legendary Koh-I-Noor. Weighing in at a massive 105.6ct, the most expensive diamond in the world is oval shaped. Steeped in mystery and legend, the stone is believed to have been mined in India in the 1300s.

Cullinan Diamond

Erasmus Jacobs

Cullinan diamond

Sediment is often deposited in layers, and each layer (bed) can reveal details such as slight changes in water conditions or even seasonal changes. One variation, cross-bedding, contains multiple sets of layers with different orientations; like ripple marks, these indicate current directions.

Sedimentary rocks are the product of 1) weathering of preexisting rocks, 2) transport of the weathering products, 3) deposition of the material, followed by 4) compaction, and 5) cementation of the sediment to form a rock. The latter two steps are called lithification.

Erosion can move sediment through water, ice, or wind. Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river’s delta. Deltas, river banks, and the bottom of waterfalls are common areas where sediment accumulates.

The terms, in order of decreasing size, are boulder (> 256 mm), cobble (256-64 mm), pebble (64-2 mm), sand (2-1/16 mm), silt (1/16-1/256 mm), and clay (< 1/256 mm). The modifiers in decreasing size order, are very coarse, coarse, medium, fine, and very fine.

The size classes used to describe clastic sedimentary rocks are, from smallest to largest: clay and silt (mud size); fine and coarse (sand size); pebbles, cobbles, and boulders (gravel size). What are the three types of sedimentary rocks?

Sediments are classified according to their size. In order to define them from the smallest size to the largest size: clay, silt, sand, pebble, cobble, and boulder.

Sand, being the larger size of particles, feels gritty. Clay, being the smaller size of particles, feels sticky. It takes 12,000 clay particles lined up to measure one inch. Silt, being moderate in size, has a smooth or floury texture.

That feel comes from the size and relative proportion of mineral particles in the soil, and is known as soil texture. The particles that make up soil are categorized into three groups by size: sand, silt, and clay.

Most beach sand color range from pale cream to golden to caramel, but in select places around the world, sands can be red, brown, pink, orange, gold, purple, green, and black.