What Does Mica Look Like?

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Mica can be a bit of a difficult mineral to identify from some other minerals.  It can look like a piece of reflective metal at times, which in turn will often get confused as a metal.  Mica is considered to be a silicate mineral and not a metal.

The good thing about mica is that when you see it a few times, there is less room to get confused about what it is.  Mica does have some very distinguishable features that can help in being able to identify what it is. 

Admittingly, some micas might be a bit more difficult to identify.  There are some mica’s out there that do not really express some of the characteristics of well known mica’s such as muscovite and biotite.  

Mica’s can be considered “part of the mica family”, such as fushsite and glauconite.  They have a “micaceous” chemical structure that places them in the mica family regardless of how it looks.  

With some of the general characteristics of the more popular mica’s, it can be quite simple to identify a specimen of mica. 

Key Characteristics of How Mica Looks

There are a few different varieties of mica available on our earth.  Some are more popular, like muscovite, than other mica varieties.  Much of mica will express some very specific characteristics to help you identify it.  You can visually identify mica by the following looks it will have:

  • It will have a reflective glassy surface:  Mica is a silicate mineral with a fairly reflective and shiny surface.  Expect this mineral to be very shiny and reflective in the sun and even look like a metal.
  • It has visible and removable flakes:  The most unique thing about mica is its characteristic of being flaky.  Small thin sheets or flakes can be broken off from the main specimen.
  • Its color:  The color of mica, not being one of its most distinguishing features, can come in common reflective colors of grays, silver, golden or yellowish browns, and black.  Some mica’s such as muscovite can be colorless, white, gray, and silvery.  Other mica’s can even have some purplish and greenish tints to it.
  • It can be quite fragile:  Mica is flaky and will often break apart when picking it up or holding it.  Expect that many specimens can shed plenty of mica flakes. 
  • Its flakes are stacked.  When you look at mica, you will not only notice that it has flakes but that those flakes are visibly stacked on each other.
  • Loose flakes can be transparent:  Often when a larger flake comes loose from a specimen, it is thin enough to see through it.  Like a sheet of small glass. 

When it comes to mica, remember that its most identifying feature is it has thin flakes.  These flakes often shed and can look like translucent fish scales as I like to describe it.   

Some Different Looking Mica Varieties

There is a nice handful of different types of mica that can be found in all rock types; sedimentary, igneous, and metamorphic.  These varieties tend to be based on its visible structure and color.  Some micas are a bit more common and abundant than others.  Some different looking mica varieties will include:

  • Muscovite:  This is quite a popular type of mica.  It has very visible flakes that can break off.  This unique form of mica will have flaky crystals that form in all different kinds of directions.  Its colors are often colorless, gray, silver, and white.   
  • Biotite:  This mica is known for being dark brown, even greenish and blackish brown.  Sometimes the flakes for biotite can be flexible.  
  • Lepidolite:  This mica is perhaps one of the more colorful forms of mica.  I have seen this one in pinks, purples, and yellows along with some of the other common colors.  The flakes for lepidolite can also be formed in different directions on the same specimen.
  • Phlogopite:  Mica in this form will express more solid and tough flakes.  It’s said the flakes can be flexible.  It commonly comes in colors of brown; such as reddish, greenish, and yellowish brown.
  • Clintonite:  This mica is a bit more rare and has aluminum, magnesium and calcium within it.  It often comes in colors of brown, yellow, orange, and green.  It can also be colorless. 

The Different Look Between Mica and Gypsum

One of the biggest identifying issues I have found with mica is with the mineral gypsum.  There is a form of gypsum, or is it mica, that other tell me is mica.  This has puzzled me, and has made me second guess my thoughts at what I have sometimes.  Some different looks between mica and gypsum are:

  • Mica has flakes:  Some gypsum will look like it has flakes, especially a desert rose, but much of the contents are in layers.  Mica will have fairly thin flakes that can easily break off.  The flakes can at times almost resemble a fish scale.
  • Mica can have other visible minerals:  Some mica can have other inclusions such as beryl or garnets visible in its contents.
  • Mica and gypsum are formed differently:  Mica will be formed in the three different rock types by a few different processes.  Much of mica is formed by the crystallization of volcanic liquids deep in the earth.  Gypsum forms by the evaporation of liquid, and the liquids contents being left behind. 

One of the most unique identifying wonders of the world is the “Cave of Crystals” (<– Wiki link), located at Naica, Chihuahua, Mexico.  Chambers in the earth at 300 meters down were discovered with massive selenite crystals (a form of gypsum).  Mica does not form in this manner, and this gypsum example is a great show in how gypsum can be formed. 

Gypsum vs Mica: On the left, is clear gypsum. On the right, is muscovite, a very silvery mica. Both these specimens are 2 to 3 lbs. You can see the distinct layering in both, however the mica on the right will flake off thin mica crystals quite easily. The gypsum on the left, being as soft as mica, will scrape off pieces, not flakes.

I have more information on gypsum with a few pictures that I have written a nice article on; “All About Gypsum” 

In the picture above, the specimen of gypsum to the left, was not easy to identify (the two specimens were given to me). I have had a couple of people tell me that it is mica. But if I go on the differences I have listed above, I moved towards it being clear selenite gypsum.

Additionally, I have done a bit of intense research on online for this specimen. I may have even identified where it came from (Glitter Mountain, St. George Utah). Picture and locations can often do wonders for identifying rocks and minerals. 

Some Different Looks Between Mica and Pyrite

Often mica will get confused with pyrite.  The biggest problem here is that some mica will glitter and shine, with similar color, just like pyrite.  There are definitely some stark differences that can help identify mica and pyrite.  Some visual looking differences between mica and pyrite are:

  • Mica comes as flakes:  Mica will be formed as flakes and pyrite will form as more solid crystal masses.
  • Mica will be lighter, less dense:  While holding mica it will not be as heavy or dense as holding in volume the same amount of pyrite.  Much of pyrite is about 50% more dense than mica.
  • Mica breaks easily.  As mica comes in flakes, this makes it easier to break off those flakes.  Pyrite does not break as easily and is a harder mineral.
  • Their streak:  When running a streak test, mica will have a white or colorless streak.  Pyrite will have a darker color in its streak, such as greenish to brownish black. 

Back in my younger days I remember seeing a bunch of this yellowish golden stuff rolling around in the rivers in my area.  I quickly thought by its appearance that it must be pyrite.  

On closer inspection, I noted that they were very small golden clumps with reflective and separable flakes.  I was able to break apart the flakes and I quickly realized that this was not pyrite at all, but mica.

Mica in Quartz Rock: This is a small sample of some quartz rock containing a visible mica vein. The mica flakes in these veins often break off and can be found rolling around in rivers and streams. Any visible sand seen under the water can glitter in the sunlight.

Conclusion

Mica is one of those interesting minerals that has a couple of unique qualities that help you identify it.  Seeing brittle and thin flakes that are stacked upon each other is in my thoughts the most identifiable thing for mica.

I have found that there are a few forms of mica in the mica family, that do not really appear to have distinguishable traits much like some of the more popular mica’s.  That is how it goes in the mineralogy world, things get defined more so by other properties such as chemical composition rather than by appearance. 

Some mica’s can be a nice addition to a rock and mineral collection.  I have some big and very nice shiny silvery specimens (images in this article).  A note to remember though if you acquire any mica specimens, they are fairly fragile, and can flake almost every time you hold them.

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