igneous

Diorite (Dalmatian Stone)

Phaneritic Plutonic Diorite

Hardness: 6-7 on Mohs scale; Color: Mottled black and white/gray; Luster: Dull to sub-vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0

Hardness: 6-7 on Mohs scale
Color: Mottled black and white/gray
Luster: Dull to sub-vitreous

Identified May 3, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-7 on Mohs scale; Color: Mottled black and white/gray; Luster: Dull to sub-vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0

Formation & geological history

Formed through the slow cooling of intermediate composition magma beneath the Earth's surface (intrusive). The dark spots are typically hornblende or biotite, while the white is plagioclase feldspar.

Uses & applications

Used in construction as crushed stone, for floor tiles, countertop material, and occasionally as a gemstone in tumbled form or cabochons.

Geological facts

Commonly referred to as 'Dalmatian Jasper' in the jewelry trade, though it is geologically an igneous rock (diorite) and not a true jasper (sedimentary chalcedony).

Field identification & locations

Identified by its 'salt and pepper' appearance with distinct interlocking crystals. Frequently found in batholiths and mountain-building zones. Collectors should look for the characteristic granular texture.

Other igneous specimens

See all

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