There are so many cool rocks and minerals to collect it’s hard to know where to start. No matter how big my own collection gets there is always something else out there that could make it just a little better. If you’re searching for some inspiration for your own collection, you’ve come to the right place.
I decided to put together this list for anyone looking for some great ideas for new specimens to add to their geological collection. Here are the best rocks, minerals, and fossils to collect:
Best Rocks to Collect
There are countless varieties of rocks in the world, but some rocks are definitely cooler than others. It’s hard to define exactly what makes a rock worth collecting, but this list takes into account how rare they are and how cool they look, all while making sure there is a lot of variety. Here are the best 10 rocks to collect:
Thunder Eggs
Thunder eggs are really awesome rocks that in many ways are similar to geodes. They are usually about baseball sized, and form when minerals like agate, jasper, quartz, or even opal fill a cavity in the surrounding rock. Unlike geodes, the cavity is entirely filled, leaving no void space, making them really great specimens to add to a collection when they are sliced in half by a lapidary.
While geodes can form in almost any kind of rock where large cavities occur, thunder eggs only occur in volcanic rhyolite ash flows. They can be found in several locations in the U.S., and all around the world. You’d probably be best off buying a thunder egg specimen unless you also have a lapidary saw at your disposal.
Oolitic Limestone
There are plenty of sedimentary rocks worth collecting, but oolitic limestone is probably my favorite because of its unique appearance. Getting its name from the Greek word for ‘egg’, this rock is made up of tiny ‘ooids’, which are themselves made up of calcium carbonate. They form when tiny pieces of sediment are washed around on the seafloor, accumulating calcium carbonate that precipitates out of the water.
I have been lucky enough to find some great oolite on the beaches in Galveston, and if you keep your eye out you can find it in many places around the U.S., especially if there is other limestone in the area.
Geodes
Pretty much every rock collection has at least one good geode. These rocks vary drastically in size and appearance, but their defining characteristic is that they have beautiful crystals encrusting the void space inside an otherwise normal looking rock. The type of crystals inside can come in almost any color and size, but the most popular type has to be amethyst – a purple variety of quartz.
Geodes, while extremely common a collectibles, can’t be found just anywhere. They can only be found in specific geologic settings where empty voids in the host rock are filled with crystals growing from mineral-rich water precipitating into them. If you think you may have found a geode I wrote a handy identification guide here.
Obsidian
We all know this unique looking rock. There is no mistaking that smooth, glassy surface and characteristic conchoidal fracturing. Obsidian makes for a great collector’s piece because of how readily available it is and how beautiful it can be. While it’s usually black, it also comes in some really pretty shades of red . You can also find it shaped into useful tools like arrowheads and knives, making it a great conversation piece.
Obsidian is very common in many places across the world because it forms from rapidly cooling lava flows on the earth’s surface. Because it’s so prevalent you can find really nice specimens for reasonable prices, or travel to many locations to collect you own.
Tektites
This is probably the rarest rock type on this list, but definitely one of the coolest. These rocks are small (about gravel-sized), glassy objects that were produced from meteorite impacts. How they form is not completely agreed upon, but basically the impact of a meteorite melted the rock at the impact size and sent it flying from the crater, at which point it rapidly cooled and landed in the surrounding area.
There are only four widely recognized areas where tektites are found, known as ‘strewn fields’, but there are many other potential locations. If you can’t make it to one of those locations to search for your own, you can find them for sale online and sometimes in local rock shops.
Granite
Some people might consider granite to be too common to put on this list, but I had to include it because it’s one of my favorites. It comes in so many varieties that you can collect many different specimens that all appear distinct from one another. The compositional varieties of the feldspars, micas, and quartz content give the granite in each location an appearance all their own.
You can collect granite just about anywhere. It’s one of the most common volcanic rocks and there are entire mountains made of it. I’d suggest collecting many small specimens from different areas instead of one large piece.
Pumice
Pumice is one of the coolest types of rocks for its famous ability to float in water. Even picking it up can be a shocking and satisfying experience – it’s so light compared to most rocks that it’s hard to wrap your head around. It can be really fun to play with, especially for kids who will have their minds blow watching a rock float in water.
Like obsidian, pumice is pretty common and readily available to any collector because of how prevalent it is. After some volcanic eruptions, it can be so abundant that the ocean surface is absolutely covered with the stuff.
Conglomerate
Conglomerate is a fun rock to collect because it’s actually just a bunch of rocks all stuck together to make one bigger rock. It can sometimes look a bit like coarse cement, and forms when large well-rounded rocks are deposited by strong water currents. The space between the rocks is usually filled with sediment and then fused together by quartz or calcite cement.
Conglomerate is very common and be found all over the world. If you find a piece that has angular grains that’s called breccia, which also makes for a nice collectible.
Lapis Lazuli
Most people think lapis lazuli (sometimes just called ‘lapis’) is a mineral because high-quality specimens are often considered gemstones, but it’s actually a rock consisting of several minerals. Its distinct blue color comes from the mineral lazurite, but it is often accompanied by other minerals like pyrite and calcite which gives it a nice variety from specimen to specimen.
Lapis is pretty rare in the U.S., but can be found all over the world – most notably in Afghanistan. Most people like to turn high quality lapis into cut gems, but the striking blue color of rough specimens makes it a nice addition to any collection.
Gastroliths
Gastroliths are rocks that have eaten by animals and used to aid in the digestion of food. They sit in the animal’s stomach or gizzard to help grind up anything they eat, and become very smooth and polished in the process. There are plenty of animals alive today that use and produce gastroliths but, in my opinion, the really collectible ones are from dinosaurs.
Since gastroliths are defined by their use in animals they can be almost any kind of rock, so you can find a lot of variety here. Many collectors will have a batch that was found together, so you can have multiple colors and rock types all from the same animal.
Best Minerals to Collect
Rocks are great, but pure minerals are usually what stand out in a collection. Their vibrant colors and well defined crystalline structure really attract the eye of admirers. There are so many amazing and beautiful minerals to collect that I’m leaving out some of my favorites, but while making this list I factored in their appearance, unique properties, variety, and availability. Here are the 10 best minerals to collect:
Magnetite
The most unique property of this mineral is definitely it’s magnetism (of course), but it can also be far more beautiful that it’s often given credit for. Pure magnetite is a really nice deep silver color and forms very nice massive octahedral crystals. Not all specimens are magnetic on their own – in fact, pieces that are naturally magnetic by themselves are known as lodestone.
Magnetite is a very common mineral but finding a specimen with nice crystalline structure is definitely more difficult. If you happen to find a piece with some good magnetism it can be fun to display it with a piece of metal attached to the side.
Rose Rock
I have a special place in my heart for rose rocks. I’m from Oklahoma, where they are our state rock. Not only that, but the land my parents’ house is on is absolutely riddled with them. Made up of the mineral barite, rose rocks get their name from their beautiful flowering structures and red color.
You can find rose rocks for sale online pretty easily, but the best place to find them is in Oklahoma. You can find them on the shores of many lakes in central OK, and Noble, OK is known as the rose rock capital of the world.
Ulexite
This isn’t the prettiest minerals around, but it’s another one that I included for a unique property. Also known as ‘TV rock’, ulexite is known for its ability to conduct light along its natural crystalline fibers. In some specimens it does this so well that you can read text through the solid mass of crystal.
Ulexite is commonly mined for its uncommonly high boron content, making it commercially valuable. Not all specimens of ulexite exhibit the unique light transmitting habit, but if you’re going to collect a piece for yourself I’d definitely try to find one that does.
Fulgurite
While technically fulgurite is a mineraloid (not a proper mineral) I had to include it here because it is so cool! It’s formed when lightning strikes a sandy area and fuses the sand grains together, often forming really cool elongated and branching clumps. I had the luxury of finding some fulgurite on a sandy hilltop in New Mexico and it remains one of my favorites.
Fulgurite can form just about anywhere that has sand or clay and is prone to lightning strikes. If you go searching yourself, look in higher sandy areas like the top of sand dunes.
Tourmaline
This gorgeous mineral was my Mineralogy professor’s favorite, and believe me when I say that is quite the endorsement. Tourmaline comes in an almost endless number of colors, often exhibiting multiple colors in the same specimen. The crystals are usually elongated and have a hexagonal habit, and most of the time they are translucent which adds to their appeal as a gemstone.
Tourmaline is an extremely popular mineral both for jewelers and mineral collectors. A really nice specimen for your collection will be more costly than many of the other items on this list, but in my opinion is well worth it.
Agate & Jasper
Okay, I cheated a little bit here in order to be able to include both of these, but they are pretty similar minerals and if one appeals to you then chances are the other will as well. Both are varieties of chalcedony, which is itself a microcrystalline variety of quartz. The easiest way to tell the difference is that agate is translucent which jasper is opaque, but they both display gorgeous bands of alternating colors.
The beautiful banded colors in agates and jaspers make them some of the most popular rocks for tumbling. If you’d like to know more about them and other great rocks to tumble I wrote about them here.
Peridot
This mineral will forever hold a special place in my heart because I got to hunt for it on a field trip my senior year of college. We found a field on the U.S./Mexico border strewn with really nice specimens that I still own today. Peridot is a pretty green form of olivine, but what really makes it special is that it forms in the upper part of the Earth’s mantle, not in the crust.
Because it forms so deep in the Earth it’s relatively difficult to find. You can only find it in places where it has been erupted onto the surface in several places around the world.
Fluorite
Also known as fluorspar, this is another classic mineral that comes in plenty of gorgeous colors including purple, blue, yellow, and green. It’s isometric crystal habit means that it often forms really nice looking specimens with well defined crystal faces. Some specimens fluoresce under UV light which has the potential to be a really cool feature in your collection.
The best fluorite specimens are usually clusters of nicely sized crystals, or sometimes one massive crystal. They form in veins and fractures in host that are subjected to hydrothermal activity.
Opal
This is another one where I’m fudging the criteria a bit – opal is technically a mineraloid because of its amorphous crystal structure. This gemstone is highly sought after by both gemologists and mineral collectors because of its unique iridescent appearance. As beautiful as cut and polished opal is, raw opal makes for a fantastic collector’s piece. It is often found within other rocks in cool patterns.
There aren’t a lot of places to find opal, but the most well known by far is Australia. You can also find it in a specific location in Idaho, which is one of the places I wrote about in this article on the best places to find crystals in the U.S.
Quartz
A good quartz specimen is pretty much an absolute must for any rock and mineral collection. Some might scoff at this suggestion because quartz is so common, but they would be forgetting that it’s also a very beautiful mineral with lots of color varieties like amethyst and rose quartz, and smoky quartz (not to mention the numerous microcrystalline varieties).
If you’re in the mood to hunt for your own quartz crystals, I wrote an in-depth article on how to do so here. If you’re not feeling that adventurous you can always find some great quartz specimens in a local rock shop.
Best Fossils to Collect
Believe it or not, some people aren’t that into rocks and minerals! Shocking, I know. But just about everyone can appreciate a good fossil, which is just one reason to add them to your collection. I tried to compile a diverse list of cool fossils here, taking into account how unique they are, how interesting they look, how they are formed, and how accessible they are to collectors. Here are the 10 best fossils to collect:
Trilobites
These guys were, at one time, some of the most successful animals to ever exist on earth. That success is now our gain because their fossils are everywhere. A trilobite was one of the first fossils I ever found while I was on a high school field trip in Pennsylvania. They are unmistakable and undeniably cool looking fossils.
Because they are so common, trilobites can be found just about anywhere on Earth with Paleozoic aged rocks. Most have well preserved hard shells, but if you really want something special (and pricey) there are some specimens that display their soft parts as well.
Coprolite
This is easily the funniest item on any of these lists. Imagine how fun it would be to have fossilized dinosaur poop! Coprolite is always good for a laugh when friends ask about it in your collection. Dinosaur poop isn’t something that comes to mind for most people when they think about fossils but, in my (admittedly sophomoric) opinion, it’s one of the cooler things to collect.
Due it the nature of coprolite it comes in all shapes and sizes. If you’re going to get your own specimen I’d recommend trying to find one that looks exceptionally… poopy!
Ammonites
These extinct mollusks are extremely recognizable, and almost every specimen I see is gorgeous. Outside the geology library I used to study in there was an ammonite fossil almost as tall as I am, but most specimens are much smaller. The vast majority of ammonoid fossils have the classic coil shape, but they come in other varieties as well.
The ribbed spiral structure of ammonites is beautiful in its own right, but if you’re lucky you can find a specimen that has been replaced with a pretty mineral or mineraloid like opal.
Petrified Wood
Petrified wood occurs when plant material (most commonly trees) is buried in sediment and then is gradually replaced with minerals like microcrystalline quartz, calcite, or opal. Its shape and structure is as diverse as the plants it’s created from, and the most impressive pieces are entire logs of ancient trees.
Petrified wood can be found all over the world. Really nice specimens will generally show some remnants of the original plan structure like tree rings. Petrified wood will usually take a pretty nice polish, making it pretty popular with rock tumbling hobbyists.
Shark Teeth
If you’ve ever searched for rocks and shells on a beach then there’s a good chance you’re found some shark teeth. One of my best friends frequently takes his sons shark tooth hunting in the Chesapeake Bay area and they almost always manage to score a handful. They aren’t the most impressive collection items on their own, but a bunch of them together look really cool.
If you do go searching for your own, I suggest going to the beach after a storm and at low tide. The heavy wave action from the storm will have churned up new material to search, and the low tide leaves more area exposed to search.
Crinoids
These fossils are pretty cool because they look a lot like plants but they’re actually animals. They are some of the most common fossils in the world, and I’ve had the pleasure of finding a few crinoid stem segments myself. Some crinoid species are still alive today, but you can find fossils that are over 450 million years old!
Fossilized crinoid stems can be found all over the world, but the really impressive specimens put the entire animal on display with their flower-like heads still attached.
Belemnites
These squid-like animals are related to ammonoids and nautiloids, and died out around the same time as the dinosaurs. The fossils are shaped like an elongated bullet because their heads were made of a hard conical shell while their soft tissue decayed away before becoming fossilized.
Belemnite fossils are often found in groups and clusters, and their size ranges from two inches to a couple of feet. The price tag will vary quite a bit between specimens but I tend to like the clusters of smaller belemnites.
Brachiopods
These are some of the most prevalent fossils in the world, and everyone who has studied paleontology at all has likely held dozens of them. They are defined by their classic two-shelled structure, but beyond that, they come in all shapes and sizes. A nice assortment of brachiopods is a welcome sight in any fossil collection.
Brachiopods are so common that they can usually be found almost anywhere. If there are other fossils around, chances are good that brachiopods are also around.
Megalodon Tooth
Unlike normal shark teeth, megalodon teeth are large and impressive enough to stand out individually in almost any collection. Their name literally means ‘big tooth’, and true to their name they are often bigger than your hand.
Megalodon teeth can be found on beaches almost everywhere in the world, but it will take some luck to find your own. They can be purchased for relatively cheap, but if you want to find your own I’d recommend searching a beach after a good storm.
Amber
Everyone knows amber when they see it. That rich golden yellow color immediately catches the eye, and that’s part of what makes it such a great fossil to collect. I always immediately think of that scene in Jurassic Park where they extract dinosaur DNA from a mosquito trapped inside a piece of amber.
Amber is beautiful in its own right, but if you’re going to collect it I’d definitely try to find a specimen with something trapped inside. Those pieces can be pricey but they are definitely worth it!