Rockhounds don’t collect limestone because there’s nothing great about it when you look at it through the lens of a rock and mineral collector. Now, if you own a house or commercial building then you probably love limestone because it’s used in the construction of these buildings and landscapers use it to build outdoor living spaces.
You’re probably asking yourself “Why are you talking about limestone if rockhounds don’t collect it?” Here’s the answer…
It’s good to have a solid understanding of host rocks because you’re going to come across rocks that will provide details or a “tell” on where to look. The better you are at identifying these rocks the better you will be at finding unique dig locations.
Limestone is incredibly beautiful and offers strength, longevity, durability, and diverse uses. It is one of the most commonly used rocks on Earth.
It’s composed primarily of calcium carbonate (Calcite) or the double carbonate of calcium and magnesium (Dolomite). It’s not uncommon to find shell fragments, tiny fossils, and various forms of fossilized debris. See I told you it would be beneficial for you to identify host rocks.
When you handle limestone you will notice it has a granular structure and it will easily rub off on your gloves or hands. It is easily scratched and will effervesce quickly in any common acid.
Limestone has two origins:
- Biogenic precipitation from seawater, with the primary agents being foraminifera and lime-secreting organisms.
- Mechanical transport and deposition of preexisting limestone, which forms clastic deposits. Tufa, travertine, chalk, caliche, micrite, and sparite are varieties of limestone.
Limestone is usually gray, but it can also be a few other colors. Keep scrolling to see every color variety of limestone.
Beige, White, and Cream
The most common color variants of limestone include beige, white, and cream. You can find Rhine White, Fine White, Ivory Cream, and Yulan Beige. These light-colored limestone varieties are often used for interior design features like fireplaces, stone kitchen hoods, and walls. Limestones in these color varieties are also used in outdoor features since their light colors reflect sunlight, keeping things cooler in hot weather.
Blue and Gray
Gray and blue limestone are much darker and somewhat sea-inspired than the white varieties. Because of the visual depth, blue and gray limestone are often used as floor tiles. Sino Blue, Azul Monica, Vert Giverny, and Ruoms Adouci are some examples of blue and gray-colored limestone.
Red and Brown
Iron oxide and clay are two impurities that are often embedded in limestone, which results in red or brown-colored limestone. Fine examples include Fontenary Dore, Chassagne Vionine, and Poiseul.
Samples with heavier amounts of “pure” limestone will appear pink or rose-colored. Hauteville C Flamme is an excellent example.
Dark Gray and Black
Pompignan and Ruoms are fine examples of limestone in darker shades like dark gray and black. The darker colors are excellent flooring materials.
Limestone can vary significantly in porosity and texture from coquina (a matrix of whole or pieces of sea shells loosely cemented by Calcite) to Oolitic limestone and microcrystalline limestone, which have structures so fine they can only be seen under a magnifying glass or microscope.
Where Is Limestone Found
Limestone is found in a variety of locations.
One of the most common places to find limestone is below marine waters. Ocean environments and conditions form large quantities of limestone because the underwater environment is rich in organisms, calcium carbonate, and animal skeletons. The shells and other components build up over time, hardening into a limestone deposit on a larger scale. Eventually, the deposits become so large that they can’t be missed.
Limestone also naturally forms through evaporation in caves where water pours through the cave floors. The calcium carbonate dissolves, forming deposits throughout the ceilings and walls of caves. The deposits build into more significant deposits throughout the years and can reach into the deepest regions of caves.
5 Uses of Limestone
Limestone has a variety of uses, and it’s used extensively in construction and road building. This material is found in aggregate, building stones, cement, chalk, and crushed stones.
- Building Material
- Raw Materials
- Soil Neutralizer
Now you know everything about limestone and you should be able to find and identify it quickly. Hopefully, you’ll find fossils, minerals, and crystals but if you don’t, no worries. You can haul away a ton of limestone and build a retaining wall in your backyard… hahaha