igneous

Indigo Gabbro (also known as Mystic Merlinite)

Gabbro (composed of Plagioclase Feldspar, Pyroxene, and minor Magnetite/Ilmenite)

Hardness: 6-7 on Mohs scale; Color: Mottled black, dark grey, and light green/white; Luster: Vitreous to sub-metallic (when polished); Crystal Structure: Phaneritic (coarse-grained) crystalline; Specific Gravity: 2.7-3.3

Hardness: 6-7 on Mohs scale
Color: Mottled black, dark grey, and light green/white
Luster: Vitreous to sub-metallic (when polished)

Identified March 24, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of magnesium-rich and iron-rich magma deep beneath the Earth's crust (plutonic formation). These specimens are often millions of years old, typically found in late Precambrian or Paleozoic formations.

Uses & applications

Primarily used for ornamental purposes, tumbled stones, jewelry (cabochons), and as a popular stone among crystal collectors and metaphysical practitioners.

Geological facts

Despite the trade name 'Mystic Merlinite', it is not a true Agate or Merlinite (Dendritic Opal). It is a plutonic igneous rock. It is prized by collectors for its chatoyant-like shifts in color when moved under light.

Field identification & locations

Identify in the field by its coarse-grained 'salt and pepper' appearance and lack of quartz. Commonly found in Madagascar, Turkey, and portions of the United Kingdom. To identify, check for a heavy weight relative to size and the presence of dark, blocky pyroxene crystals.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral