Slate

Meaning and Properties

Slate History


Slate is a common material that has been used for centuries for a variety of uses and is still used frequently today. It is most known for its use in roofing materials. However, slate is also commonly used for chalkboards, billiard tables, flooring, gravestones and landscaping.


Slate is frequently chosen over other materials because of its durable, but malleable, composition. It is also very aesthetically pleasing. The use of slate as roofing material has a history in the United States dating back to pre-revolutionary times. Slate roofs were often recommended and encouraged to fireproof construction of homes and buildings; however, this was not the first use of slate globally. Slate was a frequently used material during the Second Empire and during the Gothic Revival, High Victorian Gothic and Tudor styles.


Slate has currently seen a rise in demand and popularity due to historic preservation and the newfound realization of its superiority over other materials.

Slate Metaphysical Properties


Slate is believed by many to be a balancing stone. The stone is thought to bring balance because it is a symbol of harmony among the elements (earth, air, fire and water). As a balancing stone, it is thought to settle anxiety and balance the chakras, resulting in total inner harmony. When in balance, the chakras are more open to receiving and giving positive energies, allowing them to function at optimal capacity.


Slate Geological Properties


A foliated metamorphic rock of fine-grained clay or volcanic ash, slate is comprised of muscovite or illite and quartz. Slate is often incorrectly confused with shale as slate is a derivative of shale sedimentary rocks. Slate derives from shale due to low-grade metamorphism. The shale-type sedimentary rock undergoes low pressures and temperatures of 200-320 degrees Celsius, resulting in the production of slate. While it flakes relatively easily, it is a durable stone frequently selected to make tiles. Slate is most commonly gray in color, ranging from light to dark shades. However, slate can be found in a variety of colors including green, red, black, purple and brown, often from the same extraction site. The color composition is largely dependent on the variation of minerals present during metamorphism.


Brazil is the second-largest producer for slate extraction, the largest being Spain. While these locations produce the majority of natural slate, slate can be found all over the world with some special variations. For example, Maine is known for their slate being a dark purple color.

Chemical Composition Slate is mainly composed of clay minerals or micas as well as quartz and a small amount of Feldspar, calcite, pyrite, hematite and other minerals.
Color Light to dark gray, as well as green, red, black, purple and brown. The color of slate is determined by the amount and type of iron and organic material that are present in the rock.
Hardness 5-1/2 (Mohs)
Specific Gravity 2.65 - 2.8

Proper Care of Slate


Refrain from using vinegar or lemon juice as a cleaning agent as it could potentially etch the surface. To clean the stone, stick to mild detergents or stone cleaners with a neutral pH level. Then, rinse with water and dry with a soft cloth.


To learn more about slate and other gemstones, order your copy of Walter Schumann's revised and expanded edition of Gemstones of the World.



Designing with Slate


Slate can be used to incorporate fun and lighthearted elements in jewelry designs. This stone is frequently used in chalkboards, making it a great interactive addition to jewelry. With slate pendants or focals, personal messages or drawings can be added and replaced.


View more resources featuring slate, including Design Ideas, Videos, Tutorials and more!

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