Dr. Frederick M. Hueston, PhD 

It was one of those mornings. I was sitting at my favorite greasy spoon enjoying my cup of joe, talking– or should I say flirting – with Flo, and listening to the Admiral’s same old stories.

Just as I was about to take another bite of my Taylor ham and egg sandwich (those from New Jersey will know what I’m talking about) I overheard this loud voice coming from one of the booths. I turned around to see who it was a recognized him right away. I won’t mention his name other than to say he was one of the stone and tile industry self-proclaimed know-it-alls. Don’t get me wrong, he is a nice guy and somewhat knowledgeable but, every once in a while, I catch him spouting off on some outright made-up, what I call fantasy facts. Or should I say Fake Facts (LOL).  Just as he was telling the people he was sitting with, he looked up and saw me sitting there. He motioned me to come over and join him. I picked up my cup of joe and what was left of my sandwich and reluctantly went over and took a seat next to him. He introduced me as the Stone Detective and told his party that I would confirm what he just told them. Here we go, I thought, this is going to get interesting. He started with the fact that granite is granite and there is only one definition for granite. He went on and on, reciting the geological description of granite, and then said that if anyone tells you any differently, then they don’t know what they’re talking about. He looked at me and said, “Am I right?” He stared at me, looking for a firm Yes. I was about to agree with him so I wouldn’t have to argue and then I thought what the heck.  I stood up and said, “Yes, he is 100% correct if you’re a geologist, but in the stone industry there are actually three different definitions for granite.” Without hesitation I went into my lecture mode and blurted out the following:

Granite can be defined in different ways depending on the context.

Commercial Definition: In the commercial context, granite refers to a broad category of natural stone used in construction, architectural applications, and countertops. Commercially, granite often includes a wide range of igneous rocks with varying mineral compositions. It is commonly classified as granite based on its appearance, durability, and suitability for specific applications.

This commercial definition is broader and may encompass rocks that geologically may not meet the strict criteria for granite. As I said this, I winked at our know-it-all friend. Commercially classified granite may include rocks that are technically gabbros, syenites, or other similar types, but they are marketed and sold as granite due to their similar appearance and performance characteristics.


Geological Definition: From a geological standpoint, as my friend pointed out, granite is a specific type of intrusive igneous rock with a specific mineral composition and texture. Geologically defined granite is composed primarily of three essential minerals: quartz, feldspar (usually orthoclase or microcline), and mica (usually muscovite or biotite). It typically forms through the slow cooling and solidification of molten magma deep within the Earth’s crust.

Geologically defined granite exhibits a granular texture with visible interlocking mineral grains. The rock’s mineral composition and texture distinguish it from other types of igneous rocks. This geological definition is more precise and reflects the specific characteristics of true granite.


US Customs Definition: However, if you’re importing granite, the US Customs and Border Protection (CBP) has its own specific classification for granite. According to the CBP, granite is defined as “a crystalline rock consisting of quartz, feldspar, and mica.” This definition aligns with the geological definition but simplifies the criteria for customs purposes.

The CBP definition focuses on the three primary minerals present in granite and is used to differentiate granite from other rocks and materials during import/export processes.


I summed it up with the following statement: There are three common definitions of granite: the commercial definition, which encompasses a broad range of natural stones used in construction and countertops; the geological definition, which refers to a specific type of intrusive igneous rock with quartz, feldspar, and mica; and the US Customs definition, which simplifies the geological criteria to classify granite for import/export purposes. I tapped my friend on the shoulder, tipped my fedora to his guest, grabbed my coffee and headed back to the counter for another cup of joe and perhaps an apple turnover.  As I walked away, I thought of the following quote I once heard:  “With a perfectly timed quip, I managed to deflate the know-it-all’s argument like a balloon at a cactus convention – leaving them both deflated and wondering how they ended up in a thorny situation!”


The Stone Detective is a fictional character created by Dr. Frederick M. Hueston, PhD, written to entertain and educate. Dr. Fred has written over 33 books on stone and tile installations, fabrication and restoration and also serves as an expert for many legal cases across the world.  Send your comments to fhueston@stoneforensics.com.