Most geodes contain clear quartz crystals, while others have purple amethyst crystals. Still others can have agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, etc. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart. Read more
Large amethyst geodes can go for thousands. Baseball sized geodes with non-spectacular quartz or calcite crystals can be purchased for $4-$12. Geodes with uncommon minerals that are sold on mineral auction sites range in price from $30-$500. Golf ball sized geodes, uncracked, are sold for about $2 at shows.”
Most geode rocks have quartz or calcite crystals. Usually, quartz crystals are clear or white. When the quartz is purple, it's called amethyst.
Geodes are rocks that are hollow inside, rather than solid all the way through. Geodes are generally round, though some are egg-shaped. ... Some geodes even contain liquid petroleum. Calcite geodes contain white crystals, but sometimes these can be other colors, and under fluorescent light additional colors show up.
Geodes are found throughout the world, but the most concentrated areas are located in the deserts. Volcanic ash beds, or regions containing limestone, are common geode locations. There are many easily accessible geode collecting sites in the western United States, including in California, Arizona, Utah and Nevada.
Typically, geodes do not have gold or diamonds in them. The type of rock formations usually associated with gold is quartz, and with diamonds its kimberlite. ... Although certain quartz rock deposits have gold, it is different from the quartz crystals commonly found inside geodes.
A nodule is something roughly spherical deposited in a matrix. When the nodule has a cavity it is a geode. ... Often Chalcedony will deposit as a nodule or a geode. When the Chalcedony is banded it is an agate, although some chalcedonies that aren't banded are still called agate, like moss agate, fire agate, etc.
Although the geode is embedded in rocks that are about 250 million years old, the crystals themselves are much younger than that. Radioactive dating of some of the oldest suggests they formed less than 5.6 million years ago but probably no more than 2 million years ago, the researchers report this week in Geology .
Some people prefer using a rock saw to cut the rock in half. The rarest and most valuable geodes contain amethyst crystals and black calcite.
Geodes will typically not present with a smooth outside surface. What you'll typically find on a geode is a bumpy, uneven surface. Sometimes you can even find them with nodule like bumps on the outside surface. If it's smooth, then most likely what you have is not a geode.
Test whether the rock has a hollow interior.
Pick up the rock and assess its weight. If the rock feels lighter than that surrounding rocks, it may be a geode. Geodes have a hollow space inside, which is what allows the crystals to form. You can also shake the rock next to your ear to test whether it is hollow.
On the outside, they look like plain, rough stones. But when you break them open, you can see concentric bands of color surrounding a hollow interior. Oftentimes, that interior is packed with miniature crystals. The dull, unexceptional outside surface of a geode is part of what makes discovering one such a thrill.
Over thousands of years, these layers of minerals build crystals that eventually fill the cavity. How long this takes depends on the size of the geode — the largest crystals can take a million years to grow.
Most geodes contain clear quartz crystals, while others have purple amethyst crystals. Still others can have agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, etc. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart.
Because they are essentially hollow rock shells, geodes tumbling with other rocks in a tumbler can crack open and may be damaged. Also, tumbling removes a significant portion of the rock. In the case of geodes, it may remove so much of it that there is hardly anything left.
obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.
To find geodes, look in riverbeds, limestone areas, and volcanic ash beds in countries where geodes are often found, like the United States, Mexico, Brazil, and Madagascar. When you're searching for geodes, look for rocks that are round or egg-shaped with a bumpy texture.
Quartz is the most abundant and widely distributed mineral found at Earth's surface. It is present and plentiful in all parts of the world. It forms at all temperatures. It is abundant in igneous, metamorphic, and sedimentary rocks.
How long does it take for a geode to form? Over thousands of years, these layers of minerals build crystals that eventually fill the cavity. How long this takes depends on the size of the geode. The largest crystals can take a million years to grow!
Areas on the planet's surface that show clear evidence of fault lines and uplifts offer an ideal location to hunt for crystals. Check the area for ribbons of white quartz, which can also be found near known granite and gold deposits.
Quartz can be found in creeks almost anywhere and occurs worldwide. California, Colorado, Arizona, and Utah, and other areas in the western US are some of the best places to look. Common names are based on the rock's color, for example, clear quartz, rose quartz, smoky quartz, citrine, and amethyst.