Troctolite Rock – A Detailed Guide

Troctolite Rock – A Detailed Guide

Mar 27, 2023

The term troctolite seems unfamiliar even in the (general) construction industry, homeowners, and contractors. Troctolite is a Geo-Science term. I think Gabbro rock may sound a familiar word for you, and Troctolite is a similar kind of intrusive. Igneous rock.

Here, intrusive means the rock forms when magma or molten lava is gradually cooling on the surface of the earth and forms large crystals in the rock. If the formation process is rapid and results in smaller crystals, it creates extrusive types of igneous rocks.

What Is Troctolite? 

Troctolite is coarse-grained and consists of predominantly Olivine & Plagioclase Feldspar. 

  • Olivine is an influential rock-forming group of minerals containing Magnesium, iron silicates. It has unusual yellow to bottle-green tints due to Mg-Fe combinations in a series. 
  • Plagioclase is a member of feldspar minerals forming translucent crystals. 
  • When Olivine completely altered to serpentine, it results in a stippled appearance of green, brown, red, yellow, and black spots on the pale background. 
  • According to Britannica, the appearance resembles the skin of trout (Troctolite in German), and famously “Trout Rock” in colloquial language.

Occurrence of Troctolite

According to Wikipedia, Troctolite found:

  • The Archean Windimurra intrusion of Western Australia.
  • The Voisey’s Bay (nickel-copper-cobalt magmatic sulfide deposit) of northern Labrador.
  • The Stillwater igneous complex of Montana.
  • The Duluth Complex of the North American Midcontinent Rift.
  • The Tertiary Rhum layered intrusion of the island of Rùm, Scotland.
  • The Merensky Reef of the Bushveld Igneous Complex, South Africa.
  • The Lizard complex in Cornwall.

Country-wise Occurrence:

  • Asia
    • India, Russia
  • Africa
    • South Africa
  • Europe
    • Germany, Greece, Italy, Scotland, Turkey
  • Others
    • Greenland
  • North America
    • Canada, USA
  • South America
    • Brazil, Colombia, Venezuela
  • Deposits in Oceania Continent
    • Australia, New Zealand, Queensland

Genesis of Troctolite 

Gabbro and Troctolite are occurring together in the same magma. It means the genesis of Troctolite is closely tied to Gabbro. The main difference is in pyroxene content. Gabbro is pyroxene rich while Troctolite is missing it at all.

Troctolite cannot directly form from magma crystallization because there is no way to magma can crystalize into Olivine & plagioclase in the absence of pyroxene. There is only one possible mechanism, and it is a cumulate rock formation process where pyroxene crystals separate from magma and occur high in some regions & low in the next areas.

Thus, we can see the alternate layers of Troctolite and Gabbro with different concentrations of pyroxene. Similarly, oikocryst-bearing Troctolite and OI-bearing gabbro occur in alternate layers.

Mineralogy of Troctolite:

  • Feldspar [Plagioclase]
  • Olivine
  • Amphibole [Hornblende]
  • Mica [Biotite]

Classification of Troctolite:

  • Rock
      • Igneous rock
        • Normal crystalline igneous rock
          • Coarse-grained (“plutonic”) crystalline igneous rock
            • Gabbroid
              • Gabbro
                • Troctolite

It is the simplest way that we can classify Troctolite. Further, we can sub-divide Troctolite in the following divisions.


  1. Allivalite: It consists of Olivine & highly calcic plagioclase.
  2. Bytownite-troctolite: It chiefly contains bytownite 
  3. Harrisite: It has a matrix of Olivine composed of a rich concentration of calcic plagioclase & low presence of pyroxene. 

Properties of Troctolite:

  • Durability Parameters:
    • Water-resistant
    • Scratch-resistant
    • Stain-resistant
    • Wind resistant
    • Acid-resistant 
  • Compressive strength of Troctolite – 225 N/mm2
  • Toughness – 1.6 
  • Specific gravity – 2.86-87
  • Density – 2.7 to 3.3 g/cm3

Applications of Troctolite:

Troctolite, like Gabbro, highly useful in the dimension industry. 

The interior applications of Troctolite stones are:

  • Flooring in homes spaces like bathrooms, kitchens, living rooms, entryways, and terraces.
  • Interior decorative aggregates on window sills and various countertops in the building.

The outdoor applications of Troctolite are:

  • You can use troctolite stones as patio pavers, walling, and veneers. 
  • It is also available for the construction of roads and bridges as raw stone aggregates and blocks.
  • Arts and crafts like creative stone objects are looking beautiful with troctolite rocks. 
  • The most prominent application of troctolite aggregates is in the decoration of gardens as paving grits and landscaping, as well as in embellishment of façade walls. 

Where to find the best quality Troctolite Stones?

World of Stones USA is an ideal destination to secure top quality troctolite rock-based products. You will have adequate selection options out of a big inventory. Rates are market competitive, and post-purchase services are at par.


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