Different Types Of Geodes And How To Identify Them.

1. Introduction
2. Simple Methods for Identifying Geodes
3. How to analyze a Geode for Crystals
4. Common types of Geode
1. Amethyst geodes
2. Chrysocolla Geodes
3. Chalcedony Geodes
4. Jasper Geodes
5. Limestone Geodes
5. Conclusion

1. Introduction

Geodes are rock formations that come from volcanic lava and water. When the hot rock is cooled down over a long time, it is usually filled with quartz crystal formations.  Geodes come in a variety of different shapes, sizes, and colors.  In this article, we will be talking about the most popular types of geodes as well as how to identify them. Geodes are rounded, hollow rocks with crystal formations. Geodes can range in size from a few millimeters to several meters and they’re found all over the globe. However, most geodes that you find will be small in size. The reason for this is that as the damaged rock around a geode erodes away, the geode itself lasts for a long time. They’re made when natural crystals grow around a piece of rock or a shell in the ground. Over time, the outer layer of the mineral will harden while the inside remains soft. This is what led to the hollowed-out appearance that geodes have. 

geode - chalcopyrite on amethyst (Morocco)

2. Simple Methods for Identifying Geodes

The best way to determine what type of geode you have is by looking at the outside. If you find a stone that looks like it could be a geode, look for cracks in it. Some geodes are completely hollow on the inside, while others are only partially hollow. Sometimes there will be tiny holes in the rock through which you can see crystals growing.

Another way to determine if a stone is a geode is by looking at its size and shape. Most geodes will be perfectly round or oval-shaped, but some types of geodes may have more irregular shapes. This is determined based on where they were formed and how they were formed. Geodes come in many shapes and sizes but most commonly range from one centimeter to one meter in diameter.

Different types of Geode

3. How to Analyze a Geode for Crystals.

The first thing you'll want to do when you find a geode is testing the hardness. If it's soft, throw it away because it's probably filled with mud.  If it's hard, then give it a try. Here are some ways to tell if it's filled with crystals:

1) Look for tiny holes in the surface of the rock where crystals could grow

2) Tap on the geode with a hammer - if there are crystals inside, they should make a sound when hit by the hammer

3) Break off a small piece of the geode - if there are crystals inside

5. Common types of Geodes and how to identify them.

1. Amethyst geodes

The most common type of geode is the amethyst geode, which contains large and stunning purple crystals. Not all amethyst geodes contain crystals of the same size or shape. Some geodes contain small, needle-like crystals that resemble a cluster of grapes. Others contain large crystals that look like quartz stalactites.

• How to identify Amethyst geodes

When held up to the light, you'll notice that amethyst is a translucent purple color with white streaks running through it. When you break a piece off the main amethyst crystal and hold it up to the light, you'll see light shining through like an opal. You may also find some amethyst geodes with brown or white lining around the center cavity. These are known as "drusy" and they usually have very small white crystals growing inside them. The amethyst drusy looks like a piece of sandstone or petrified wood and usually has white or brown calcium deposits on the outside wall of the geode cavity.

Amethyst geode (South America)

2. Chrysocolla Geodes

Chrysocolla geodes are generally found in places such as Arizona, New Mexico, Australia, Chile, Russia, and England. They have been around for over five thousand years and were once used by the Egyptians to make jewelry. The chemical composition of chrysocolla is copper hydroxide silicate. Chrysocolla is a secondary mineral that occurs when water gets into areas with copper ores. The color of chrysocolla can vary from a bright blue to a greenish-blue. It is often found with malachite and azurite.

• How to Identify Chrysocolla Geodes

The inner surface of these geodes will be lined with green or bluish-green chrysocolla, and they sometimes contain a mix of different minerals.

Chrysocolla Geode containing Quartz Crystals

3. Chalcedony Geodes

Chalcedony is a mineral that is made up of microcrystalline quartz. These geodes usually form in sedimentary rock, and they are formed by hot springs that have erupted through limestone. Chalcedony geodes have been found in Utah and California, but they have also been found in Brazil and Morocco. These geodes can come in various colors, including white, pink, reddish-brown, grayish-blue, and black. They can also be spotted or banded, and they sometimes have druzy crystals on their surface.

• How to Identify Chalcedony Geodes

Look for a rock with a gray or brown outer shell. If you can’t find one that is cracked in half, then put it in a freezer overnight to help crack it open. Inside you should see some purple or blue crystals that were formed by quartz mineral deposits.

 Chalcedony Geode containing Fluorite

4. Jasper Geodes

Jasper geodes are made from Chalcedony, a mineral that has multicolored bands of blue, red, yellow, and brown. Some jasper geodes have very little color while others have vivid bands of different colors. Jasper is often cut into cabochons for jewelry because it has a hardness rating of 6.5-7 on the Mohs scale. Jasper is an opaque mineral that comes in a variety of colors including pink, green, red, and white.

• How to Identify Jasper Geodes

Jasper (silicon dioxide) is an opaque form of chalcedony quartz that comes in a wide range of colors from browns to reds and greens to purples. The mineral is formed from slowly cooling molten rock, which is why jasper can be ornately patterned with flecks or stripes of color. Jasper geodes are similar in appearance to limestone geodes but they're much harder and weigh more due to their higher iron content. A good place to look for jasper geodes is in basaltic lava flows or volcanic ash beds.

 JASPER GEODE | These nodules of red Jasper

5. Limestone Geodes

Limestone geodes are more commonly found in sedimentary rock layers and are often mistaken for fossils because they have a crystallized center that looks like a fossil shell. Limestone geodes come in many different sizes and shapes and can be found in almost every continent on earth including North America, South America, Africa, and Asia. They can also be found underwater on riverbeds and lakeshores where they have been eroded over time by water currents.

• How to identify limestone geodes

Calcite crystals line limestone geodes. They are often gray or tan on the outside, but inside you'll find sparkling purple amethyst or clear quartz crystals. Some limestone geodes have large crystals that fill the entire cavity inside the stone! Limestone geodes are typically found in Brazil and Mexico.

 Geode with quartz, calcite, and barite (Harrodsburg, India)

6. Conclusion

Collectors all want to learn how to identify geodes, whether they go out looking for them or not. Geode hunters often refer to them as brain rocks because they look similar, in certain circumstances, to the shapes of brains. Actually, geodes are formed inside giant crystals; and many different crystals can create a variety of different geode shells. Some of the most common crystal types used in geode formations include quartz, calcite, and pyrite, among others. Only the general shape and color of a geode will help you identify what it contains without breaking the rock apart.