Carbonate Petrography

Carbonate petrography is the study of limestones, dolomites and associated deposits under optical or electron microscopes greatly enhances field studies or core observations and can provide a frame of reference for geochemical studies.

25 strangest Geologic Formations on Earth

The strangest formations on Earth.

What causes Earthquake?

Of these various reasons, faulting related to plate movements is by far the most significant. In other words, most earthquakes are due to slip on faults.

The Geologic Column

As stated earlier, no one locality on Earth provides a complete record of our planet’s history, because stratigraphic columns can contain unconformities. But by correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a composite stratigraphic column, called the geologic column, that represents the entirety of Earth history.

Folds and Foliations

Geometry of Folds Imagine a carpet lying flat on the floor. Push on one end of the carpet, and it will wrinkle or contort into a series of wavelike curves. Stresses developed during mountain building can similarly warp or bend bedding and foliation (or other planar features) in rock. The result a curve in the shape of a rock layer is called a fold.

What Is Rock?

What Is Rock? 

To geologists, rock is a coherent, naturally occurring solid, consisting of an aggregate of minerals or, less commonly, of glass. Let’s take this definition apart to see what its components mean. 
  • Coherent: A rock holds together, and thus must be broken to be separated into pieces. As a result of its coherence, rock can form cliff or can be carved into sculptures. A pile of unattached mineral grains does not constitute a rock. 
  • Naturally occurring: Geologists consider only naturally occurring materials to be rocks, so manufactured materials, such as concrete and brick, do not qualify. 
  • An aggregate of minerals or a mass of glass: The vast majority of rocks consist of an aggregate (a collection) of many mineral grains, and/or crystals, stuck or grown together. Some rocks contain only one kind of mineral, whereas others contain several different kinds. A few rock types consist of glass. 

Something Precious, Gemstones

Something Precious, Gemstones

The Hope Diamond.
Mystery and romance follow famous gems. Consider the stone now known as the Hope Diamond, recognized by name the world over (figure above). No one knows who first dug it out of the ground (See Where Do Diamonds Come From?). Was it mined in the 1600s, or was it stolen off an ancient religious monument? What we do know is that in the 1600s, a French trader named Jean Baptiste Tavernier obtained a large (112.5 carats, where 1 carat 200 milligrams), rare blue diamond in India, perhaps from a Hindu statue, and carried it back to France. King Louis XIV bought the diamond and had it fashioned into a jewel of 68 carats. This jewel vanished in 1762 during a burglary. Perhaps it was lost forever perhaps not. In 1830, a 44.5-carat blue diamond mysteriously appeared on the jewel market for sale.

Mineral Classification

Mineral Classification 

The 4,000 known minerals can be separated into a small number of groups, or mineral classes. You may think, “Why bother?” Classification schemes are useful because they help organize information and streamline discussion. Biologists, for example, classify animals into groups based on how they feed their young and on the architecture of their skeletons, and botanists classify plants according to the way they reproduce and by the shape of their leaves. In the case of minerals, a good means of classification eluded researchers until it became possible to determine the chemical makeup of minerals. A Swedish chemist, Baron Jöns Jacob Berzelius (1779–1848), analyzed minerals and noted chemical similarities among many of them. Berzelius, along with his students, established that most minerals can be classified by specifying the principal anion (negative ion) or anionic group (negative molecule) within the mineral. We now take a look at principal mineral classes, focusing especially on silicates, the class that constitutes most of the rock in the Earth.