Rockhounding in Florida – What Rocks You Can Find and Where

Upcoming Rockhounding Events in Florida

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Agatized Coral

Agatized coral occurs when silica in the ocean water hardens, replacing the limy corals with a form of quartz known as chalcedony. This long process (20-30 million years) results in the formation of a “pseudomorph,” meaning that one mineral has replaced another without having lost its original form. In 1979 agatized coral was designated the official state stone of Florida.

Photo: Fossil Agatized Coral Florida by Wilson44691 is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.

Aragonite

Aragonite is a carbonate mineral that shares it’s chemical structure with calcite. Aragonite differs from calcite in its crystal structure, an orthorhombic crystal system. Aragonite’s tendency to form multiple twinned crystals results in pseudo-hexagonal forms.

Aragonite is also produced by some living animals. There are some variety of mollusk whose entire shell is made up of aragonite. Some creatures produce nacre, or mother of pearl, which is composed of hexagonal platelets of aragonite. This organic-inorganic composite material is known for its iridescent appearance.

Dolomite

Streak: white

Hardness: 3.5-4

Chemical Formula: MgCO₃

While the rock form of dolomite is common and closely resembled limestone, mineral dolomite can be found in certain places in Ohio. Found in Northwestern Ohio in association with many other minerals, dolomite can range in color from white to brown to pink.