Why is limestone good for fossils

There are places in Fort Worth, Texas where there are slabs of rock containing these devil's toenails by the million. As the rocks decay out of the sides of outcroppings, there are piles of these shells sitting loose.

Very amazing indeed. Trevor, It's amazing to find fossils like this anywhere. I'm afraid that we can't identify or comment about any without good photographs though. If these are from Texas it might be worth you contacting your nearest museum with a geological curator.

Trevor- where in Texas? I have alot of these. I continue to find these till this day on my grandfather's land here in texas. If I could have more information on these I would love it. Are they worth anything? Jenny Kenward. Hi I am starting a small collection of rocks and minerals for my grandson and each one will have a info card with it. Could you give me a bit of information about them.

Many thanks. My mum got me a largeish chunk of limestone with a few visible shells in it. I'm disolving it in white vinegar is such a thing doable? How often will I have to change the vinager? My goal isn't to totally disolve it just expose hidden fossils inside. The limestone comes from keates quarry in Dorset near where they found the dinosaur tracks. Cindy Smith. When pure, travertine is white, but it is often stained by the presence of other minerals to cream, tan, greenish, brownish, and other colors.

Because the precipitation is rapid and forms as encrustations on younger materials, travertine is often a banded rock with numerous voids and cavities. It sometimes contains inclusions of organic and mineral debris from the cave or surface environment.

Travertine was mined and used as an architectural stone in ancient Egypt and ancient Rome. Today, Egypt and Italy are famous sources of travertine that is exported throughout the world. It is sawn or sheared into floor tiles, window sills, wall panels, stair treads, and other shapes, mainly for interior use.

High-quality material can sometimes accept a polish. The material can be recognized by its low hardness 3 on the Mohs scale , banded appearance, and porous texture. Tufa is a porous rock that forms from the precipitation of calcium carbonate, often at a hot spring or along the shoreline of an alkaline lake where waters are saturated with calcium carbonate. Tufa is a porous limestone produced by precipitation of calcium carbonate from the waters of a hot spring or other body of surface water that has the ability to precipitate volumes of calcium carbonate.

The pore space in tufa often results when plant material is trapped in precipitating calcium carbonate. One of the most famous locations where tufa is actively forming is at Mono Lake, Yosemite National Park. The most spectacular tufa features at the lake are known as "tufa towers". They form by the interaction of freshwater springs and alkaline lake water. In spite of its gnarly appearance as a rock, tufa actually has numerous architectural uses. When found in thick accumulations, tufa can be mined and sawn into blocks and sheets just like any other dimension stone.

It produces a stone with a very rugged appearance. Crushed Limestone: The Unsung Mineral Hero: Crushed stone is often looked upon as one of the lowliest of commodities; however, it is used for such a wide variety of purposes in so many industries that it should be elevated to a position of distinction.

It is the geologic commodity upon which almost everything is built. The Wordle word cloud above shows just a few of its many diverse uses. Limestone is a rock with a diversity of uses. It could be the one rock that is used in more ways than any other. Most limestone is made into crushed stone that is used in road base, railroad ballast, foundation stone, drainfields, concrete aggregate, and other construction uses.

It is fired in a kiln with crushed shale to make cement. Some varieties of limestone perform well in these uses because they are strong, dense rocks with few pore spaces. These properties enable them to stand up well to abrasion and freeze-thaw. Although limestone does not perform as well in these uses as some of the harder silicate rocks, it is much easier to mine and does not exert the same level of wear on mining equipment, crushers, screens, and the beds of the vehicles that transport it.

In many parts of the world, the harder silicate rocks are too far from construction sites to be used economically. A Gem of Crinoidal Limestone: This cabochon was cut from a piece of fossiliferous limestone that is rich in crinoid debris.

Crinoids are organisms that have the morphology of stemmed plants but are actually animals. Rarely, crinoidal and other types of limestone have the ability to accept a bright polish and have interesting colors and patterns. These specimens can be made into unusual and beautiful organic gems.

This cabochon is about 39 millimeters square and was cut from material found in China. The Loyalhanna is a Late Mississippian calcareous sandstone to arenaceous limestone, composed of siliceous sand grains embedded in and bound by a matrix of calcium carbonate. In outcrop, the Loyalhanna is cross-bedded with features that have caused geologists to argue if it is of marine bar or eolian dune origin.

As a construction material, the Loyalhanna is valued as an anti-skid aggregate crushed stone. When it is used to make concrete paving, sand grains in aggregate particles exposed on a wet pavement surface provide traction for tires, giving the pavement an anti-skid quality.

Limestone has many other uses. Powdered limestone is used as a filler in paper, paint, rubber, and plastics.

Crushed limestone is used as a filter stone in on-site sewage disposal systems. Powdered limestone is also used as a sorbent a substance that absorbs pollutants at many coal-burning facilities. Limestone is not found everywhere. It only occurs in areas underlain by sedimentary rocks. When limestone is needed in other areas, buyers sometimes pay five times the mine-site cost of the stone in delivery charges so that limestone can be used in their project or process.

The best way to learn about rocks is to have specimens available for testing and examination. Article by: Hobart M. Limestone Stalactite A water drop clings to a stalactite. If it evaporates instead of falling, any dissolved calcium carbonate will add to the stalactite. National Park Service photo. Find Other Topics on Geology. Maps Volcanoes World Maps. What Is Limestone? Hardness Picks. Rock, Mineral and Fossil Collections. Flint, Chert, and Jasper. Tumbled Stones. Fluorescent Minerals.

Lapis Lazuli. Rocks: Galleries of igneous, sedimentary and metamorphic rock photos with descriptions. Fossils become a part of sedimentary rocks when sediments such as mud, sand, shells and pebbles cover plant and animal organisms and preserve their characteristics through time.

Mud forms when larger rocks erode into tiny, usually microscopic, particles. These particles settle in the calm waters of lakes, swamps and the ocean, covering creatures that live there.

Mud and clay combine with minerals and other particles over time to harden into shale. The hard parts of the creatures covered with mud undergo preservation as fossils when consolidated with other materials inside the shale.

Shale splits easily into layers to reveal any fossils inside. Fossils inside shale often include brachiopods, fossilized plants, algae, crustaceans and arthropods trapped in the hardened mud.

The very small mud and clay particles allow small details of organisms to be preserved, like the rare fossils of soft-bodied organisms found in the Burgess Shale. Limestone forms when calcite from the water crystallizes or when fragments from coral and shells cement together.

Limestone often contains fossils of shelled sea creatures. Entire reef formations and communities of organisms are found preserved in limestone. The types of fossils found in limestone include:. Most limestone forms in shallow tropical or subtropical seas. In some cases, fossils make up the entire structure of limestone. Cemented together grains of sand become sandstone. Since sandstone is a coarser material than shale or limestone, fossils found in them do not usually show as many details as fossils in shale and limestone.

Sandstone rarely contains delicate fossils. Sandstone forms in a wide range of environments, including beaches, oceans, sand bars, dunes, rivers, deltas, deserts and flood plains.