What Does Obsidian Look Like?

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Obsidian is one of those rocks that can be hard to identify for the inexperienced.  There are a few other types of rocks or minerals on our earth that can express the same appearance as obsidian.  

The great thing about obsidian is that once you have seen and held a few specimens, it can be easy to identify thereafter.  

Obsidian is considered a rock and not a mineral.  This is primarily due to it not having a mineral defining crystal structure.  There are many black rocks and minerals on our earth that can end up being confused and identified as obsidian.  

Key Characteristics of What Obsidian Looks Like

Obsidian has some very distinguishable features that really help identify it.  Luckily, many of these distinguishable features are visual and don’t require any actions, such as scratch tests, to help you identify the rock.  You can visually identify obsidian by the following:

  • Its glassy appearance.  When obsidian is broken the fresh surface looks like black glass. If the broken piece of glass is thin enough, you can see through obsidian like glass.
  • It can be sharp.  Some obsidian when broken can break in a way that makes it sharp.  Some very thin and sharp pieces of obsidian can be sharper than a razor blade.
  • It has no crystal shape.  Obsidian will have the appearance of a rock and never take on any natural crystal structure like minerals can.
  • It’s smooth appearance.  Being a glassy looking rock, the surface of the rock can be quite smooth to the touch, especially if it’s the surface of a fresh break.
  • It is brittle and can be easily broken.  It does not take much to break a piece of obsidian with a hammer or other hard surface. 
  • It can have a conchoidal fracture.  Not all obsidian when broken will easily show a conchoidal fracture, the ones that do will show a smooth surface with lines or ripples in it, like a seashell.

If you are looking at obsidian in the field, you might note that much of the obsidian is not as shiny as you would think.  It typically takes breaking one of those rocks in half to express the shiny surface obsidian has.

Some obsidian found will look like tiny little black rocks.  They might be somewhat round, and even be a little bit shiny.  These have been given the name “Apache tears”, and they have likely rolled around for some time, maybe down a river.  The friction from all the movement has rounded them out into small pebbles.

Rough Obsidian to Clean Break: On the left is a show of a specimen of obsidian that looks much like a common roundish rock. On the right is the break of that same specimen, showing a nice glassy and shiny surface after the break.

Obsidian Varieties Will Look Different

Obsidian does have a few varieties.  These different varieties have to do with color and patterns within the rock.  Some obsidian varieties with a different visual look will include:

  • Black obsidian, is the most common obsidian available, and generally is the color black.   
  • Snowflake obsidian, has the appearance of black obsidian but with white spots on it.  Those spots often look like small snowflakes.  
  • Sheen obsidian, will have reflective colors such as gold, silver, green and purple.
  • Mahogany obsidian, will have a reddish to brownish color.  Often there can be examples of this obsidian that will express the black with spots of the brownish and reddish mahogany with it.
  • Firework obsidian, is obsidian that will contain much of the same appearance as snowflake obsidian with those white flakes on it, however, those snowflakes can be more intricate, like sea coral, and additionally have red within it.  Expect more of a concentration of those flakes as well.
  • Spider web obsidian, as it sounds, looks like it has white webs intertwined within the black obsidian.

Identifying the different varieties of obsidian can be fairly easy.  Many of the varieties will have a name that almost describes it on its own.

Some of the varieties of obsidian are quite the favorite for many.  You can often see these varieties displayed or added in jewelry.

Mahogany Obsidian: On the top you will see what is known as a mix of black obsidian with mahogany obsidian.

The Different Look Between Obsidian and Tourmaline

Obsidian and tourmaline will often get confused with each other.  There are some very distinguishable differences between the two that will help you identify them both.  Some visual looks between obsidian and tourmaline are:

  • Obsidian does not form in crystals, as it does not have any crystal system.  Tourmaline is a mineral and has a trigonal crystal system which shapes as a parallel and elongated crystal.
  • Tourmaline will often have parallel lines running along its elongated crystal, obsidian will never express these lines on its surfaces.
  • Obsidian can have pieces with extremely sharp edges, while tourmaline will not break into sharp pieces like obsidian. 

The key to identifying obsidian and tourmaline apart will be primarily visual.  Obsidian will display as black rocks, while tourmaline will display as lined and elongated crystals.  Some tourmaline crystals don’t show these lines very easily but they will still be in a crystal looking form.

Obsidian vs Tourmaline: To the left we have a distinct elongated and lined crystal of tourmaline. On the right shows a glassy and shinny surface of obsidian.

Different Look Between Obsidian and Onyx

Trying to identify between obsidian and onyx can be perhaps one of the most difficult identifying tasks.  These two can be so close in appearance that they can be easily confused.  However, there are some good characteristics available to help you in identification.  Some visual looks between obsidian and onyx are:

  • Much of raw obsidian will look exceptionally shiny, like glass, while raw onyx will typically show as a dull looking rock.  
  • Obsidian does not have banding, onyx is a form of chalcedony, and much like some jaspers, it can have some nice parallel banding.
  • Obsidian can have smoother surfaces, onyx will look more like a rough rock with rough surfaces. 
  • Onyx will not chip and break as easily as obsidian. 
  • When obsidian is chipped or broken, you may have a strong visual of the ripple lines on the surface.  You will not see this when chipping or breaking onyx.

When obsidian gets weathered a bit, it can lose that very shiny look.  This is where it can end up dull enough to look like onyx, which can create some visual identification troubles.

There are a large number of people on the internet selling onyx.  If you look closely at their images, you will note in a number of them, that the image is actually obsidian. 

This really bugs me, hence part of the reason for me to write some visual ways for you to identify between the two.

Conclusion

Some of the key characteristics to identify obsidian are its glassy and shiny appearance.  Its surface on a break will show that conchoidal fracture, or the ripple lines.  It is quite brittle and breaks easily.  Additionally, its surfaces will be very smooth on its breaks.

Once you see obsidian and its varieties a few times, it can get much easier to identify obsidian thereafter.

For some additional information on the rock obsidian, you can access my article here; “All About Obsidian”.  This article will detail more about obsidian.

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