Types of Rocks In the Cayman Islands: A Guide to the 7 Most Common You’ll Spot 

The Cayman Islands contain some of the most amazing stones. In this article, you’ll learn more about the geology of the Cayman Islands.

Types of Rocks In the Cayman Islands: A Guide

Disclaimer

The information provided in this article by YesDirt.com is for informational purposes and is subject to change. Laws are updated. Accessibility guidelines and restrictions change. Be sure to confirm the land status and collection rules before you travel to an unfamiliar location or collect any material.

Introduction

The Cayman Islands are almost completely composed of limestone, embedded in the limestone are deposits of caymanite, a local semi precious stone.

There are also many types of limestone including crystalline limestone and calcarenite.

There are layers of volcanic basalt and granite under the thick limestone cap. 

The limestone formations are striking as it has been shaped by karst action and contains many fossils. 

The Cayman Islands, located in the Western Caribbean Zone in the Greater Antilles, is the most populous and highest standard of living island nation in the Caribbean. 

The three islands that make up the Cayman Islands have closely related geology. 

Caymanite 

Caymanite is a stone that was first recorded in the Cayman Islands in the 1970s and is used as a semi precious stone today in lapidary on the islands. 

Caymanite is a rare form of dolomite that has vivid earth colored layers. It is most commonly white, but can be found in red and black varieties. 

It has a pearly luster and a hardness of 3.5 to 4. The stone is often polished into beads for use in jewelry. 

Caymanite is found in Cayman Brac and near Pedro Castle in the Cayman Member geological formation. 

There is a permanent Caymanite display at the Cayman Island National Museum where you can see all different types of caymanite. 

You can support the local economy by purchasing beautiful caymanite examples and jewelry in the craft market or Kirk Freeport in Grand Cayman. 

There are also caymanite beads and chips available to purchase from vendors based in the Cayman Islands. 

Caymanite has also been found in Hungary and southern Whales. 

Limestone

Limestone is a common rock to find on the Cayman Islands. This rock is formed from the remains of ocean life as it breaks down into calcium rich sediment and cements together into a relatively soft stone that often contains fossilized remains of shells and marine animals. 

The Cayman Islands contains several striking examples of limestone formations. 

Hell is a town on Grand Cayman with a large karst limestone formation that contains many fossils. 

The limestone in Hell is unusually dark gray to black. The stones jut up from shallow water and have a very eerie appearance. 

If you view a broken piece of limestone from the Hell formation you will see that the black color is mostly on the outer layer and the inside of the stones is lighter in color. 

The limestone in Hell has been shaped by erosion and wind to form conical columns. 

Hell is a tourist location where you can get suvineeres that play on the town’s name. There are gift stops, shopping and plenty of accommodations available to tourists. 

Calcarenite

Calcarenite is formed from larger particles of calcium containing particles. These particles are high in calcium and are generally of marine origin. 

Calcarenite is very similar to sandstone in that the texture is similar although the composition is very different. 

Calcarenite is a carbonate rock. 

Calcarenite was originally named in 1903 by geologist Grabau when he was describing the stone by the size of the individual particles. 

Because of its compositions, calcarenite often contains recognizable pieces of shell or coral. It may also contain larger fossils.  

Granodiorite

Granodiorite is a granite-like stone that forms when lava is pushed close to the crust of the Earth, but not through the crust. The stone forms as the lava cools over time. 

This fine grained gray rock contains a higher volume of feldspar and about 20% quartz. 

The Cayman Islands are tectonically active and there are many areas where the lava could have moved from deeper layers in the Earth to form granodiorite.

Granodiorite is somewhat related to caymanite as they are often found in similar regions. 

Terra Rossa 

Terra Rossa is a very red clay soil that fills gaps in the limestone in the Cayman Islands. 

These beautiful deposits compress over time into some of the bright layers of caymanite. 

Terra Rossa is derived from limestone as it weathers.

This is a striking geological feature in the Cayman Islands that is not found on other islands in the region. 

The distinct layers of terra rossa on Grand Cayman can be seen on the buffs in Pedro Castille and the Cayman Member. 

The soil may compact down into very hard clumps, but they will dissolve in water and crumble under pressure. 

Coral Fossils

Grand Cayman has a large limestone deposit that contains many examples of fossilized coral. 

The interesting thing about the limestone on Grand Cayman is that there is very old limestone and relatively young limestone. 

They are layered above and below a layer of volcanic basalt. 

These layers contain fossils from two very different points in history and some striking examples can be seen at the National Museum as part of the Ira Thompson Collection.

The collection also includes many interesting artifacts from the original inhabitants of the islands. 

Rocks on Cayman Islands

The Cayman Islands have a few unique and interesting rocks that can be found only on these three islands. 

Be sure to obey any posted signs and local laws concerning collecting rocks, shells or sand on these islands. 

Lapidary is alive and well on the island, so consider purchasing local stones as jewelry to support the local economy. 

Those interested in the geology of the Cayman Islands should start on Grand Cayman and visit the bluffs. 

This is the most studied area of the islands and contains examples of all the stones and formations mentioned in this article. 

The Cayman Member region of the bluffs contains many caves that are lined with hard dorite. The types of diorite are varied.  

This is interesting as the neighboring region of Pedro Castle contains virtually no diorites and no caves. There is the common terra rossa that fills the gaps in both formations. 

The conservation efforts in the area are in early stages. NGOs in the area are still working to secure land for conservation. 

There are a few National Parks where the collecting and removing of any natural material is not permitted. 

Types of Rocks In the Cayman Islands