The deserts and mountains of Southern California are beautiful, and they also house an amazing array of different gems and minerals. For those willing to brave a bit of sun and sand this is a great region for rockhounding, with the potential for finding some very rare stones if you know where to look.
So, let’s dig into the various rocks and minerals you can find in sunny Southern California and where you should start looking!
Rocks, Minerals and Gemstones Found in California
Tourmaline is a famous gemstone, whether you’re a fan of the deep colors of rubellite and indicolite or prefer it in the color-zoned watermelon tourmaline configuration. It just depends on what you’re into. The area inland of San Diego hosts pegmatites that contain some of the best tourmalines in the world, along with some of the rarest varieties like the rubellite mentioned above and indicolite.
Tourmaline is, in most cases, a deep black color. This type of tourmaline is known as schorl and it’s the most common type by far, making up more than 90% of the tourmaline found worldwide. On the other hand, tourmaline also exists in incredible colors, ranging from earth tones to deep saturation that can compete with the best of rubies and emeralds.
Across this part of the state it’s possible to find pegmatites. These are large-grained stones, where the “grains” are usually crystals that range from a few centimeters to over a foot in length. These are a common host for tourmaline, and separating them carefully is how the crystals are best found. Colors in this region range across the spectrum, but rubellite is particularly “common.”
If you’re interested, the best place to start looking is near the famous tourmaline mines to the Northeast of San Diego. There are many of them, and some even allow public access, but access changes based on the season and individual mine.
2. Beryl (Morganite)
In the same pegmatites that host tourmaline, you can also find a few varieties of beryl. The clear sort is the most common, but there’s also a surprising amount of the pink variant known as morganite. Beryl is one of the larger families of gemstones, containing such favorites as emerald, aquamarine, and heliodor in addition to morganite.
While Southern California doesn’t have a heap of different varieties, it is a source of gem-quality morganite. Gem-quality beryl is clear and has few internal fractures, allowing it to be cut into faceted gems for jewelry. Beryl isn’t a rarity, it can be found in various igneous rocks across the world, but finding locations with a consistent coloration in gem-quality is rare indeed.
Beryl, like tourmaline, tends to be found as one of the base constituents of pegmatites. These stones are rich in unique minerals, and are one of the best sources of gemstones found in the USA. The varieties differ but the same constituents can usually be found within them, with tourmaline and beryl both being among the most commonly found minerals in their makeup.
The morganite of Southern California is found in the same pegmatites as tourmaline, to the northeast of San Diego. Here the best samples are often found in the same mines, making it a good spot to start cracking open some stone.
Garnet is another famous gemstone, and it’s also found in Southern California. Garnet actually describes a large group of different minerals with different colors, but the most commonly known are almandine garnets of the red variety. In SoCal, the main draws are gem-grade spessartine garnet and grossular garnet.
Garnets are most often found in metamorphic stones like marble. The majority of garnet is destined to end up being used as an abrasive in cutting processes, including the use of industrial waterjets which favor the use of almandine garnet. The mineral breaks in a way that it’s always “sharp” which makes it ideal for this kind of use.
On the other hand, gem-grade garnets are frequently cut for jewelry. The main varieties found as gem-grade samples in SoCal are spessartine garnets, which are a deep orange color and have good clarity. That said, a lot of garnets are pulled from the various areas in this region of different grades and types.
The best places in Southern California include areas in both San Bernadino and San Diego Counties. In particular Ramona, California is known to produce the aforementioned gem-grade spessartine garnets.
Gypsum is a common mineral, and one that’s more important to the modern world than many realize. Indeed, you’re probably sitting a few feet from some at max since it’s the primary ingredient used to fill in the sheetrock used in construction. Of course, powdery white “something” isn’t exactly the most inspiring mineral for collectors. Instead, most people seeking out gypsum formations in the Southern California desert are looking for the distinct shape of desert roses or the beautiful crystals of selenite.
Selenite is one of the most famous minerals, known for growing into large crystals. It has the odd property of actually being able to be bent, a rare trait indeed among crystals. It lacks elasticity, however, so any bent pieces are going to remain bent afterward. Desert roses, on the other hand, are masses of tabular crystals of sand-included gypsum which form into unique shapes.
The desert roses found in California can be quite rare and tend to have a more jagged appearance compared to those from Arizona and New Mexico. The selenite, on the other hand, tends to be crystal clear although some have taken on a yellowish tint from various impurities that were included when it formed.
The best of both can be found in Inyo County, which is a great place to start if you’re on the hunt for some gypsum.
Read More: A Guide to Collecting Selenite
Gold is a huge part of California’s history, and while we generally talk about the Sierra Nevada region when we’re discussing the California Gold Rush there’s also a lot of gold in the Southern part of the state. To this day people still head to SoCal hoping to strike it rich in the rivers and streams of the area.
Gold has been responsible for a lot of human history. While not of immediate value, like steel, the fact that it’s pretty and doesn’t oxidize made it a useful store of value, since purity could often be easily determined. While we’ve switched to a different kind of currency these days, gold remains a valuable mineral and is often used in electronics as well as jewelry.
Across the entire state it’s not uncommon to be able to find a bit of color in the pan when you dip into streams and creeks. While some areas are better than others, the truth is that it’s a popular past time in California and it’s usually not too hard to scare up a few milligrams of gold as long as you’re not on the far Eastern edge of the state.
For those in SoCal there are plenty of options, but I’d stick your best bet on the San Gabriel River and associated waterways, which are still known to house plenty of alluvial gold deposits.
The big three of the cryptocrystalline silica world are jasper, agate, and chalcedony. All three are found in large amounts across much of Southern California, both in the deserts and along the beaches. Indeed, beaches across the entire state are known to wash up some great samples of these stones on a regular basis.
These stones are all chalcedony-based. Chalcedony itself is a complex intermixture of moganite and quartz, two crystalline forms of silica that form into a complex microstructure when combined. These materials seem waxy or glassy at first glance, it actually takes a special microscope and exceptionally thin layers to be able to detect the crystal structure of these minerals.
Within California there’s a dizzying array of different types, it just depends on the location that they eroded from. Some of the best locations sport all three types and even complex arrangements like brecciated jasp-agate which is jasper that was broken down and reformed later with clear chalcedony.
The hot spots aren’t easy to find but the beaches along the Southern portion of the state and adjoining waterways are your best bet to bring home something beautiful.
Geodes are hollow rock formations that contain crystals, generally in a round or potato-esque shape. The deserts of Southern California boast one of the best places in the world to find them, making it a hot spot for those who can handle the heat. The geodes in the state are generally some kind of quartz, with clear quartz being the most common.
Alongside geodes, you may also find the occasional thunderegg. Thundereggs are solid nodules of chalcedony that lack the internal hollow of geodes. They can be a bit harder to distinguish from other rocks since they don’t ring hollow or have a lower weight than the surrounding stones in many cases. They’re still good to keep an eye out for when you’re hunting.
The geodes from this part of the state come in a few varieties of quartz. Smoky and amethyst quartz geodes are also found here, but they’re rare compared to the more common clear formations. They’re generally found in areas of past volcanic activity, where digging through the ancient ash is quite easy.
The Hauser Geode Beds are the best place to look, and we’ve written a guide to them in the past.
8. Fire Agate
Fire agate is clear chalcedony with botryoidal inclusions of iron oxide. These inclusions are incredibly thin, which gives them an iridescent effect as light plays over them. The majority of the stones are clear chalcedony and the layers of iron contained inside are vanishingly thin which makes them difficult stones to cut. They’re only found in a few places, and Southern California happens to be one of them.
Fire agate is in a different league than most agate when it comes to pricing. High-grade fire agate is worth a lot of money after being cut, and there are even artisans who specialize in carving them to preserve extra material and color that can be lost when they’re cut en cabochon. Fire agates are one of the hardest stones for a lapidary to cut properly, and years can be spent exploring their beauty and quirks.
Fire agate is one of the few agate varieties that has found a place in high-end traditional jewelry. A good piece can be worth a ton of money and the skilled labor required to process them properly makes the price even higher. Lower grade stones can be found for a decent price, but as the size increases and the cut’s complexity goes up so does the worth of the stone.
If you’re looking to gather some fire agate of your own then you’ll want to check out the Mule Mountains of Riverside County. Many of the hotspots aren’t revealed but plenty of prospectors bring amazing material in from that area.
Topaz is a hard gemstone that comes in a few colors. Oddly enough, the color favored for the simple use of “topaz” has changed from a brown-yellow close to citrine to a sky blue color that’s fond often in the jewelry trade. The majority of the blue material that shows up has been irradiated since the radiation will bring out the blue color in the majority of clear topaz. This treatment is so routine that it’s not disclosed most of the time, but if you have blue topaz then chances are it was subjected to the process.
Topaz is a silicate mineral and naturally occurs in many different colors despite the fact that most of it is clear. It’s harder than quartz crystals, sitting at an 8.0 on the Moh’s scale, which is similar to minerals like beryl. It’s also very rare, even in less than stellar grades, and it’s a favorite to hunt for many hobbyist gem hunters. The combination of high price and rarity makes hunting for these stones a bucket list item for many.
The topaz of SoCal is almost uniformly colorless. On rare occasions, it will show a bit of blue and on even rarer ones you’ll see a light green color. These aren’t typical finds, but the good news is that the majority of the material from California is gem-grade prismatic crystals. While not overly large, they’re still a significant find for most collectors.
The area around Ramona in San Diego County is the best place to search for topaz in this region. It’s often found in the same areas as garnet.