What are the Differences Between Rocks and Minerals

The differences between rocks and minerals are that a mineral is a natural occurring solid chemical compound which is formed as a crystalline structure.  Rocks are formed of naturally occurring solid masses that typically consist of one mineral but can be made of a combination of minerals as well. 

Minerals will also occur naturally in its pure form and their composition will remain unchanged. Rocks are categorized by the minerals contained within them.

Many don’t think about rocks and minerals being different. Often people say a rock is a mineral and even more say a mineral is a rock. Of course there are also those that are not so concerned about being “geologically correct” and don’t worry about it. There are definitely some defining differences between rocks and minerals. This article will go over those differences by first discussing rocks and then getting into minerals.

What are Rocks?

Rocks are solid masses consisting of different types of minerals in different chemical compositions. They are formed within the earth, or on the surface of the earth, through the means of weathering, pressurizing, or heating and cooling of magma or lava.

There are 3 different types of rocks:

• Igneous Rocks – Igneous rocks are a type of rock formed from the cooling of magma.  The Magma is made up of melted rock material which can contain one or multiple minerals.  More on igneous rocks; How are Igneous Rocks Formed?
• Metamorphic Rocks – Metamorphic rocks are a type of rock where the transformation of already formed rocks are made to be more dense or compact.  More on Metamorphic rocks; How are Metamorphic rocks Formed?
• Sedimentary Rocks – Sedimentary rocks are a type of rock that is formed on ocean floors or other bodies of water by the accumulation of particles that are mineral or organic; More on Sedimentary rocks.  How are Sedimentary Rocks Formed?

Temperature Range at Which Rocks Will Melt

The temperature range rocks will melt will be between 600 to 1,300 degrees Celsius.  That’s 1,100 to 2,400 degrees Fahrenheit.  These temperatures only exist very deep beneath the surface of the earth where rock is turned into magma.

This process is part of the rock cycle and how rocks change in that rock cycle. 

The Flow of the Rock Cycle

The rock cycle is a process in which rocks are continually changing through the 3 types of rocks.  The typical rock cycle involves changes from igneous to sedimentary to metamorphic and back through to igneous again by the volcanic process of heating and cooling. 

This specific cycle does not have to be exactly in this order for rocks to change to a different type.  Also keep in mind, it can take millions of years for rocks to undergo changes through these 3 types.

For more information on the rock cycle take a look at this post “Diagram of the Rock Cycle Explained“. This is a great article getting into some detail about the rock cycle diagram.

The Many Uses of Rocks

Rocks are used for many applications in our everyday lives such as landscaping, roads, sidewalks, buildings, barriers, sculptures, damns, decorations, fuel, and many more.  The big differences in the uses between rocks and minerals are primarily in that rocks are commonly used as building and construction material.

Collecting rocks, or rockhounding as it is called, is where individuals go out to certain locations and find specific rocks in that location. A lot of the time finding the rock and collecting it is the adventure for a rockhounder, and it is typically a hobby rather than any sort of business. (link to rockhounding)

Rockhounders like to display or show off their collections at times to others and more often than not, there are plenty of stories to go with each location the rocks were found.

Some Interesting Rock Facts

Aside from some of the basic facts about rocks that exist such as one who studies rocks is called a geologist, there are some interesting rock facts that don’t get mentioned very often.

• We know that igneous rocks come from magma in the earth, hence the word “Igneous” which comes from the Latin word “ignis” which means “of fire”.
• The mining of rocks for their mineral contents has been one of the most important things done in the advancement of human history.
• The colors that can be within rocks have been used for many years by artists for paintings and coloring of materials.
• Myths and legends have been around for many years when it comes to various types of rocks.  Today, many believe there are healing powers contained within rocks and minerals. These healing powers are thought to help people physically and spiritually when certain rocks and minerals are worn, carried, or just in the nearby area.

What is a Mineral?

A mineral is best described as a naturally occurring inorganic solid within rock. It has a specific and mostly repeating chemical composition. This means a mineral cannot contain organic life and it should have a continuous chemical bond holding it together with few impurities.

For a mineral to be natural it means it was not created by humans.  These minerals are naturally found as a solid and not as a gas or liquid. 

An organic mineral would mean that the material consists of living organisms of which minerals do not.  Minerals have an ordered and specific composition of molecular structure, which are repeated over and over to create a solid mass of the mineral.

One would call an organic mineral an organic compound which means that the mineral consists of carbon. These organic minerals are rare and are put into 3 classes: hydrocarbons, salts, and organic acids.

The Seven Types of Minerals

The seven types of minerals are carbonates, halides, oxides and hydroxides, native elements, phosphates, silicates, and sulfides. These different types of minerals have been classified into these types of minerals based on their chemical composition and the crystal form that they take.

The seven types of minerals are classified into these groups:

• Carbonates – A carbonate mineral is a mineral that contains the carbonate ion.  A great example of this mineral can be found here “All About Calcite“. Carbonate minerals have many variances and are commonly found in chemically precipitated sedimentary rock.
• Halides – Halide minerals have the five halogen elements; chlorine, bromine, fluorine, iodine and astatine.  An example halide mineral can be found here “All About Fluorite“. These minerals are considered a binary compound meaning there are two minerals present.
• Hydroxides and Oxides – Hydroxide minerals are of the hydroxyl groups such as manganite, while oxides can consist of corundum and hematite.  A hydroxide consists of an oxygen and a hydrogen atom and carries a negative electric charge. An oxide has a chemical composition that has at least one oxygen atom and one other element.
• Native Elements – Minerals made of a single element are called native elements. Native elements are some of the well-known elements such as gold, silver, and copper. Diamonds are also thrown into the precious native element category as they are made up of pure carbon.
• Phosphates – Phosphate minerals have a high concentration of phosphate minerals. Apatite is one of the most abundant of this type of mineral.  Most other types of phosphates are quite rare.
• Silicates – Silicates are the most common and important of all the minerals available, these can consist of beryl, quartz, feldspars, tourmaline, mica, pyroxene, garnet, and many more.  Roughly 40% of the most common minerals are silicates.
• Sulfides – Pyrite is a very common occurrence of a sulfide mineral throughout our world. Think of sulfides as containing sulfur. You can read up on pyrite as a sulfide mineral here “All About Pyrite“.

There are thousands of minerals on the earth that have been recognized by scientists. There are only few handfuls of common minerals that we use most commonly in our everyday life.

What are Minerals Made of?

Minerals are made of one or more combined elements you would find on the periodic table of elements. Elements found on the periodic table will be combined by chemical bonds to form the molecules that make up a mineral.

How Are Minerals Formed?

Minerals are formed from two available ways; One, crystallization of magma as it cools within the earth’s crust or on the surface where lava will cool in the atmosphere.  Two, Crystallization of the materials as they are dissolved in water.

As these minerals cool to a solid state, they form crystals.  The size of these crystals depends on how slow or quick it cools.  The slower the cooling the larger the crystals.  This typically means the closer to the surface the cooling happens, the quicker it happens.

How are Minerals Identified?

Minerals are identified by their physical properties of hardness (measured on the Mohs scale), color, luster, fracture, tenacity, streak, fracture, cleavage, and specific gravity.  These different ways to identify a mineral are not often used to identify rocks.

The most important identification used for a mineral identification is its hardness.  This hardness is described as the ability to visibly scratch the mineral with another mineral or object.  The very popular scale that is used for this is commonly called the Mohs scale of hardness, created by Federick Mohs.

The scale goes from 1 to 10, with the mineral Talc being a 1 and the mineral diamond being a 10.  A mineral higher on the Mohs scale is capable of scratching a mineral lower on the Mohs scale.

A common testing kit can be created to help identify the hardness of a mineral.  This kit can include; copper penny (3 Mohs), common nail (4 Mohs), pocket knife (5.5 to 6.5 Mohs), window glass (5.5 Mohs), and some steel (6.5 Mohs).

With this kit you can attempt to scratch the surface of a mineral you might have, which will help you with identification.   

The Many Uses of Minerals

Minerals are used for all applications in life as they are in our buildings, roads, computers, furniture, and even in our food.  If you can think of it, then it likely has minerals in it.  One of the well-known uses of minerals is jewelry…

Jewelry will include rings, necklaces, pendants, earrings, and pretty much anything worn as jewelry contain minerals such as gold, silver, copper, nickel, and even brass.  It does not stop there, did you know that those diamonds, rubies, emeralds, sapphires, and other gemstones are also minerals.

Rocks and Minerals, A Tight Relationship

The relationship between rocks and minerals are minerals will usually be found within rocks. This relationship is a tight one as rocks will contain all the elemental ingredients and physical environment for minerals to be formed. Often if you can identify the rock, you can identify the potential minerals that may be within it.

Known rocks will not always produce a specific mineral within them in for all cases. The degree of elemental composition and past environment will not always be the same for any specific rock.

There are plenty of examples of a similar rock being found in different locations. One location will produce large crystals while the other location will not produce any crystals at all. Keep in mind though, even though you may get different mineral results from different locations, often you will find close or same results as well.