Home Tourmaline Black Tourmaline vs. Obsidian: What is the Difference?

Black Tourmaline vs. Obsidian: What is the Difference?

by Madonna

Gemstones have fascinated humans for centuries, not only for their beauty but also for their supposed metaphysical properties. Among the darker stones, Black Tourmaline and Obsidian often come up in discussions, especially in contexts of protection and grounding. Though they may look similar to the untrained eye, these stones are quite different in their origins, compositions, and properties. In this article, we’ll delve into the key differences between Black Tourmaline and Obsidian, exploring their unique characteristics, benefits, and how to identify them.

Origins and Formation

Black Tourmaline

Black Tourmaline, scientifically known as Schorl, is a member of the complex boron silicate mineral group known as tourmalines. These minerals are found in a variety of colors, but Black Tourmaline is particularly valued for its deep, opaque hue. Black Tourmaline forms in igneous and metamorphic rocks, typically crystallizing in pegmatites and granitic veins. It can also be found in sedimentary rocks, formed through the weathering and transport of pre-existing tourmaline crystals.


The formation process of Black Tourmaline is slow and occurs under high-pressure conditions deep within the Earth’s crust. This prolonged formation process allows for the development of its distinctive prismatic, striated crystals, which can range in size from small grains to large, well-formed specimens.



Obsidian, on the other hand, is a natural volcanic glass formed from the rapid cooling of felsic lava, which is rich in silica. Unlike Black Tourmaline, Obsidian is not a mineral but a mineraloid due to its lack of a crystalline structure. Its formation is a quick, almost instantaneous process, as the lava cools so rapidly that atoms are unable to arrange themselves into a crystalline structure, resulting in a glassy, amorphous solid.


Obsidian is typically found in areas with recent volcanic activity. Its appearance is often smooth and glass-like, and it can break with a characteristic conchoidal fracture, creating sharp edges. This rapid formation process and lack of internal structure give Obsidian its unique properties, distinctly different from those of Black Tourmaline.

Composition and Physical Properties

Black Tourmaline

The chemical composition of Black Tourmaline is complex and varies, but it primarily consists of sodium iron aluminum borosilicate. Its formula can be written as NaFe3Al6(BO3)3Si6O18(OH)4. This composition gives Black Tourmaline its characteristic black color and contributes to its hardness and durability.

Black Tourmaline has a Mohs hardness of 7 to 7.5, making it a relatively hard stone. It has a specific gravity of around 3.2 to 3.3, which makes it denser than many other gemstones. The stone exhibits a vitreous to sub-vitreous luster, and its crystals are often well-formed with distinct striations running parallel to the length of the crystal.


Obsidian’s composition is primarily silica (about 70% or more), with various other trace elements and compounds depending on the specific type and source of the lava. Its chemical formula is less definitive due to its amorphous nature, but it is generally considered to be (SiO2) with impurities.

Obsidian has a Mohs hardness of about 5 to 5.5, making it softer than Black Tourmaline. Its specific gravity is approximately 2.4 to 2.6, making it less dense. The lack of a crystalline structure gives Obsidian its glassy luster and smooth texture. It also has a notable conchoidal fracture, which means it breaks into curved, shell-like pieces with very sharp edges.

Metaphysical Properties and Uses

Black Tourmaline

In the realm of metaphysical and healing properties, Black Tourmaline is often regarded as one of the most powerful protective stones. It is believed to absorb negative energies and convert them into positive ones, providing a shield against electromagnetic radiation and psychic attacks. Many people use Black Tourmaline for grounding and balancing, as it is thought to help connect the wearer to the Earth’s energies.

Black Tourmaline is also associated with the root chakra, which is the energy center responsible for grounding and stability. It is said to promote a sense of security and reduce feelings of fear and anxiety. In addition to its protective qualities, Black Tourmaline is thought to aid in detoxification and support the immune system.


Obsidian, particularly Black Obsidian, is also highly valued for its protective qualities. It is believed to create a shield against negativity and psychic attacks, much like Black Tourmaline. However, Obsidian is also known for its reflective properties, which are thought to bring hidden emotions and thoughts to the surface. This can lead to deep personal insights and emotional healing.

Obsidian is often used for grounding and connecting with the Earth’s energies, similar to Black Tourmaline. It is associated with the root chakra as well, providing stability and protection. In addition to its metaphysical properties, Obsidian has been used historically for making tools and weapons due to its sharp edges and durability.

Identification and Differentiation

Visual Inspection

One of the simplest ways to differentiate between Black Tourmaline and Obsidian is through visual inspection. Black Tourmaline typically appears as elongated, prismatic crystals with striations along the length of the crystal. Its surface may appear slightly textured due to these striations. In contrast, Obsidian is generally smooth and glassy, with a uniform texture and conchoidal fractures.

Hardness Test

The Mohs hardness test is another effective method for distinguishing between the two stones. Black Tourmaline, with a hardness of 7 to 7.5, will be more resistant to scratching compared to Obsidian, which has a hardness of 5 to 5.5. This test can be conducted by attempting to scratch the surface of the stone with a material of known hardness, such as a steel file (hardness 6.5) or a quartz crystal (hardness 7).

Specific Gravity Test

Specific gravity, or density, is another distinguishing factor. Black Tourmaline, being denser, will feel heavier than Obsidian of the same size. This test can be performed by weighing the stone and comparing its weight to its volume to determine its density.

Fracture and Cleavage

The way a stone breaks can also provide clues to its identity. Obsidian breaks with a characteristic conchoidal fracture, resulting in sharp, curved edges. Black Tourmaline, on the other hand, does not typically exhibit conchoidal fractures and may break along its striations or crystal planes.

Applications in Jewelry and Decoration

Black Tourmaline

Black Tourmaline is popular in jewelry, often cut into cabochons, beads, or faceted stones. Its durability and distinctive black color make it suitable for various types of jewelry, including rings, necklaces, and bracelets. Black Tourmaline is also used in decorative objects, such as sculptures and carvings, and in metaphysical practices, it is often kept in raw form or as polished stones.


Obsidian is also widely used in jewelry, typically fashioned into cabochons, beads, or intricate carvings. Its smooth texture and glossy finish make it a favorite for pendants, earrings, and other ornamental pieces. Additionally, due to its historical use in tools and weapons, Obsidian is often crafted into replicas of ancient artifacts. In metaphysical practices, Obsidian is commonly used in its natural form or polished into spheres, pyramids, or other shapes.

Care and Maintenance

Black Tourmaline

Black Tourmaline is relatively easy to care for due to its hardness and durability. It can be cleaned using warm, soapy water and a soft brush. Ultrasonic cleaners and steamers are generally safe to use, but it’s always best to check for any inclusions or fractures that might make the stone vulnerable to these cleaning methods. It’s advisable to store Black Tourmaline separately from other gemstones to prevent scratches.


Obsidian, being softer and more brittle, requires more careful handling. It should be cleaned gently with warm, soapy water and a soft cloth. Avoid using ultrasonic cleaners or steamers, as the stone’s glassy nature makes it susceptible to thermal shock. Obsidian should be stored separately from other stones and protected from sharp blows or pressure that could cause it to fracture.

See Also: Can Black Tourmaline Go in Salt?


While Black Tourmaline and Obsidian may share some visual similarities and protective qualities, they are distinct in their origins, compositions, and properties. Black Tourmaline, with its crystalline structure and boron silicate composition, offers durability and strong protective energy. Obsidian, a volcanic glass, provides reflective and grounding properties with a smoother texture and sharp edges.

Understanding these differences not only helps in identifying these stones but also in appreciating their unique qualities and benefits. Whether you are a gemstone enthusiast, a jeweler, or someone seeking the metaphysical benefits of these stones, knowing the distinctions between Black Tourmaline and Obsidian can enhance your experience and use of these fascinating gemstones.


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