Basalt vs Azomite: What Are They and What’s the Difference?

Basalt and Azomite – What are they and how are they different?

If you’re interested in rocks, or gardening, these two minerals are ones you might be interested in.

Basalt vs Azomite: (Summary)

Basalt and Azomite are two different types of rocks and rock dust that can be found in volcanic regions. Their individual compositions are somewhat different, but their basic origins are very similar.

Basalt and Azomite are often used for enriching garden soils, due to their high content of minerals.

They can both be found through mining the remains of volcanic explosions.

What is Basalt?

Basalt is a dark, fine-grained volcanic rock.

It’s the most common of igneous rocks, formed by the rapid cooling of certain forms of volcanic lava.

Basalt is generally formed in the earth’s crust, melted and forced to the surface.

Many volcanic islands, such as Hawaii, are made primarily of basalt rock and dust.

Basalt is found in the same category of rocks as obsidian and granite.

How Can You Identify Basalt?

Basalt is a heavy black or dark grey rock, sometimes found with a reddish or greenish crust.

In texture, it has a fine grain and a smooth texture.

It has no discernable crystals, and is a dull color when it’s been freshly broken apart.

It is less glassy than obsidian, and not as strong as granite.

What Are The Properties of Basalt?

  • Igneous rock
  • Dark in color
  • Rich in iron and magnesium
  • Fine grained and compact structure, sometimes glassy in color sheen
  • Scores a 6 on the Moh’s hardness scale for minerals, making it comparable to iron
  • Rarely found in a porous state, usually fairly dense

Where Can Basalt Be Found?

Basalt is found in cooling lava flows.

It has a thin viscosity in comparison to other forms of volcanic substances, which allows it to rise to the surface and form thin streams and sheets of material.

It can also be found on volcanic islands, where it often forms as much as 90% of the surface.

What is Azomite?

Azomite is a naturally occuring mineral compound, often mined as a compressed dust from ancient volcanic sites.

It has a large percentage of silica and other minerals used to enrich soil.

Azomite is thought to be produced when volcanos erupt into the seabed.

As the ash and the sea floor dried out over the centuries, the particles became a fine, intermixed sandy substance.

The name is an acronym, referring to it’s nickname of ‘the A to Z of minerals’.

How Can You Identify Azomite?

Azomite is generally a yellowish dusty substance

Contains 67 trace elements and minerals.

Coarse, irregular particles.

What Are The Properties of Azomite?

  • Azomite is high in minerals and nutrients
  • It’s a coarse, irregular crystalline dust
  • High in silica and other minerals
  • It’s not actually a single mineral or type of stone, but a composite
  • It has no defined hardness

Where Can Azomite Be Found?

Azomite is most commonly found near ancient volcanic sites, where the ash has been mineralized and compacted.

The most common location for finding and mining azomite is in the deserts of Utah, in what used to be sea floors.

How Are Basalt and Azomite Similar?

Basalt and azomite are similar in several respects.

  • They are both the byproducts of exploding volcanos
  • High in nutrients and minerals
  • Used for a number of gardening purposes, particularly enriching depleted soils

How Are Basalt and Azomite Different?

  • Basalt is produced by cooling lava flows. Azomite is produced by volcanic ash.
  • Basalt a singular mineral compund. Azomite is a composite, compressed dust.
  • Basalt is a hard, igneous rock. Azomite is most often found in a sand-like state.
  • Basalt is dark in color. Azomite in it’s natural state is a paler, tannish sand.
  • Basalt is found in multiple locations. Azomite is found primarily in Utah.
  • Basalt is formed within the Earth’s crust. Azomite is formed of materials within the volcano, and on the Earth’s surface.
  • Azomite has more silica and significant minerals. Basalt has more iron and magnesium.
  • Basalt is verified to be found on the Moon and Mars, whereas there is no known source of Azomite on either surface.

What Are They Used For?

Basalt and Azomite are used for many things.

Their mineral content is particularly good for enriching poor soils and restoring those that have been depleted through farming or other activities.


The primary use for Azomite is for fertilizers and soil additives.

Azomite can be used as part of compost and fertilizers.

It is used to produce a greater yield of fruits and vegetables.

The naturally occuring minerals are safe for plant life, as well as humans and animals.

Most fruits and vegetables benefit from application of Azomite dust to the soil, at least in the proper quantities.


Basalt dust or crushed basalt rock is an excellent fertilizer. Good for soils that need more iron and magnesium.

Basalt, as a dense rock, rather than a dust, can also be used for other things. Uses include:

  • Decorative landscaping
  • Floor tiles
  • Countertops – Especially useful in the kitchen, since they’re resistant to acids and staining.
  • Walls and and thermal insulation
  • Broken up and used as an aggregate for roads and asphalt.

Why Do People Confuse Basalt and Azomite?

There are two thing that confuse people about Basalt and Azomite: Their origins and their uses for soil replenishment.

Since both sets of minerals come from the byproducts of erupting volcanos, it can be a source of confusion as to which one comes from which source.

Basalt and Azomite also have different uses in terms of replenishing the minerals in depleted soils.

When Do You Use Basalt vs Azomite?

Basalt offers more heavy metals.

Basalt is a better choice for soils that are in need of iron or magnesium.

Azomite is the best choice for soils that need silica replenishment or a wide range of other minerals.

Basalt and Azomite: Wrap Up

Despite their differences in composition and color, these two types of minerals share many similarities, the main two being their volcanic origin and their usefulness in nourishing plant life. 

If you’re an avid gardener, either of these can be of immense help in maintaining healthy soil, and growing large, healthy plants.

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Basalt vs Azomite