Santa Cruz Garnet
Typically, when you think of rock hounding there's a lot of variables to consider. You have to know where you're going, how to get there, what equipment you'll need, etc..
This particular blog posts will tell the story of the most leisurely rock hounding trip I've ever been on.
Let's start with the location. As you may know, Santa Cruz is a beachfront town with small mountain ranges surrounding the coast, this particular location leads to a lot of interesting geology and therefore, rock hounding! Now, as a Californian, I've been to this particular beach hundreds of times! I've taken hikes around all the parks, been to countless beaches, and I've definitely picked up hundreds of rocks, but nothing I found was quite like this piece! As you may be able to tell from the picture, what I found was a Mica Schist with little Almandine Garnet inclusions. Mica Schist is a fairly common mineral, and while Garnet itself is a semiprecious gemstone; as well as the birthstone of January, It's not considered to be particularly uncommon. I was surprised to find the stone, seeing as I have never heard of garnet form SC, but I'm not so surprised at where I found it.
Mica Schist forms as small, reflective mineral "sheets" that can range from large slabs to plate-like mineral grains. Their formation is also somewhat indicative of how the mineral formed. This mineral forms at convergent plate boundaries when shale and other clay minerals are subject to compression forces and subsequent heat and radiation in a process known as metamorphism. The combined heat and pressure essentially squishes these minerals into a parallel alignment perpendicular to the direction the pressure comes from. Pretty much like stacking pieces of paper. The result of the increased levels of heat and pressure turns these fine-grained minerals into thin platy metamorphic minerals like Mica, Biotite and Schist. When this occurs it is also essentially a breeding grounds for certain gem-like minerals to form! One of these minerals being Almandine Garnet.
The formation of Garnet can almost be seen as directly reliant on the processes that allow Mica and Schist to form. You see, Garnets occur as a result of pushing, displacing, and replacing the minerals already present in the shale. During metamorphism chemical bonds are broken, meaning that the minerals recrystallize into minerals that can be stable under the new levels of temperature and pressure. Therefore certain mineral inclusions indicate what processes occurred at the time of it's formation. The color is specifically reliant on already present Aluminum and Iron.
After formation, it's common for these minerals to be displaced or moved from where they formed. Whether this be through tectonic movement or other processes is up in the air really, at least in the case of this particular specimen.
It's likely that some event such as an earthquake or a shift in plate tectonics exposed a particular section of shale with an abundance of these minerals to the elements. I theorize that this section came up somewhere directly off the coast of the Boardwalk in Santa Cruz. There, the moving tides and overall weathering from the ocean broke it up into chunks, and washed them up on the beach. Just waiting for the next person to come across it. Who knows how many millennia it waited. Patiently enduring it's own demise, bodying the constant weathering and decay, hoping to one day be freed of the terrible existence under water. Praying for the next fool to come along and deem it worthy of being a collectors item. And celebrating in rejoice when it was I to be that fool.
The rock hounding trip itself was amazing, because it wasn't actually a rock hounding trip at all! The honest to goodness best way to find crystals is to just be super fucking lucky I guess man. All that being said I found it by stepping on it while frolicking about in the ocean
- Ya boii Chris