Augite

Augite is a common dark-colored clinopyroxene mineral, best known as a major rock-forming silicate in basalt, gabbro, diabase, and many mafic to intermediate igneous rocks. In the hand, it usually reads as black, greenish black, dark green, or brownish black, with a weighty, dense feel and a vitreous to dull surface depending on freshness.

Collectors look for short prismatic to blocky crystals, dark granular grains in volcanic matrix, and two good cleavages meeting near right angles. With a Mohs hardness of 5.5-6, augite is moderately hard but brittle, so sharp edges and terminations deserve a padded tray rather than a loose box.

Augite was named in 1792 by Abraham Gottlob Werner from the Greek word “auge,” meaning brightness or luster. The name points to the sometimes bright vitreous shine seen on fresh crystal faces, even though weathered pieces can look dull, earthy, or brownish.

In mineral collections, augite is valued less as a showy gem and more as a direct record of iron-, magnesium-, and calcium-rich magmas. For label checking, collectors often compare classic locality names such as Mount Vesuvius and the Eifel volcanic district with mindat.org records before placing a specimen in a study drawer.

Augite is found worldwide because it is a major mineral in basaltic and gabbroic rocks. It is reported from Italy, Germany, France, the United Kingdom, Norway, the United States, Canada, Mexico, Brazil, Japan, New Zealand, Russia, Australia, and India.

Augite forms by crystallization from iron-, magnesium-, and calcium-rich silicate melts, especially in mafic igneous rocks such as basalt and gabbro. Its chemistry is variable, with substitution of magnesium, iron, calcium, aluminum, titanium, and minor sodium within the pyroxene structure.

Specimens may come from basalt flows, alkaline igneous rocks, volcanic bombs, skarns, and high-grade metamorphic rocks derived from basaltic or carbonate-rich protoliths. In a fresh broken volcanic rock, augite often appears as dark grains or compact prisms beside feldspar, olivine, hornblende, or other volcanic minerals.

Identify augite by its dark color, short blocky to prismatic habit, monoclinic pyroxene character, and two good cleavages meeting at about 87 and 93 degrees. Thin edges may show translucent green or brown, while the streak is usually white, grayish white, or pale greenish gray.

The most useful field separation is from hornblende: augite cleaves nearly at right angles, while hornblende cleaves at about 56 and 124 degrees. Augite is harder than apatite but softer than quartz, generally non-magnetic to very weakly magnetic in ordinary hand samples, and commonly sits as dark grains in basalt, gabbro, or volcanic matrix.

Intact augite specimens are generally safe to handle. The main practical risk is inhaling mineral dust if the specimen is cut, drilled, crushed, or ground.

Rough/Tumbled: Common rough or matrix specimens are often about $2-$20; well-formed crystals from classic volcanic localities may sell for $20-$150 or more depending on size, sharpness, locality, and associated minerals.

Cut/Polished:

Value is driven by crystal size, sharpness, luster, intact terminations, contrast on matrix, and provenance from classic localities such as Vesuvius or the Eifel district. Augite is not commonly faceted as a gemstone because it is usually too dark and has only moderate durability.

Moderate — Scratch resistance: Harder than most household dust and apatite, but softer than quartz, topaz, corundum, and many gem materials., Toughness: Brittle; crystals can chip along cleavage planes if struck or dropped.

Augite is generally stable under normal indoor conditions. Weathered specimens may have dull surfaces or alteration products, and crystal edges should be protected from abrasion.

Use & Storage

Store augite specimens in a padded box or display case, especially if crystals have sharp edges or delicate terminations. Keep separate from harder minerals such as quartz that can scratch it.

Cleaning

Clean with lukewarm water, mild soap, and a soft brush. Avoid ultrasonic cleaning for fractured or matrix specimens because cleavage and internal cracks may be damaged.

Cleanse & Charge

For metaphysical use, cleanse by placing on dry selenite, using smoke, or setting near clear quartz. Avoid harsh salt treatments that may damage associated matrix minerals.

Placement

Place in a study, rock collection, or earth-themed display where its dark color and igneous origin can be appreciated. It pairs well with basalt, feldspar, olivine, and other volcanic minerals.

Caution

Do not use acids or aggressive chemical cleaners. Avoid dropping, hammering, or tumbling collectible crystals, as augite is brittle and cleaves readily.

In modern crystal-healing traditions, augite is used as a grounding stone associated with stability, focus, endurance, practical decision-making, and volcanic earth energy. These meanings are spiritual beliefs, not medical claims, but they fit the specimen’s physical character: dark, dense-looking, and strongly tied to igneous rock.

For metaphysical care, place augite on dry selenite, use smoke, or set it near clear quartz. Avoid harsh salt treatments that may damage associated matrix minerals, and store collectible crystals away from harder minerals such as quartz so the vitreous faces and cleavage edges stay intact.