Aquamarine with Schorl Inclusions

Mineral (Beryl variety with Tourmaline inclusions)

Be3Al2Si6O18 (Beryl variety with Tourmaline inclusions)

Also known as: Included Aquamarine, Aquamarine with Black Tourmaline

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Description

Aquamarine with Schorl Inclusions is a variety of the mineral beryl (Be3Al2Si6O18) characterized by its blue to blue-green color and the presence of black, acicular (needle-like) or prismatic crystals of schorl (black tourmaline). The aquamarine itself is typically transparent to translucent, and the schorl inclusions can range from sparse, delicate needles to dense, radiating aggregates. The contrast between the pale blue aquamarine and the dark black schorl creates a distinctive and often aesthetically pleasing appearance.

How to Identify

Color: Aquamarine matrix is typically blue to blue-green; schorl inclusions are opaque black.
Luster: Aquamarine is vitreous; schorl is vitreous to resinous.
Texture: Smooth, glassy feel for aquamarine; schorl inclusions are typically prismatic or acicular, sometimes appearing as fine needles or radiating sprays within the aquamarine.
Crystal Form: Aquamarine forms hexagonal prisms, often with flat terminations. Schorl forms trigonal prisms, often with striations parallel to the c-axis, and can be acicular or columnar within the beryl.
Cleavage: Aquamarine has imperfect basal cleavage {0001}. Schorl has no distinct cleavage, exhibiting conchoidal to uneven fracture.
Geological Environment: Granitic pegmatites, hydrothermal veins, and greisens associated with granitic intrusions.

Key Facts

Hardness: 7.5-8 (Aquamarine, Mohs scale); 7-7.5 (Schorl, Mohs scale).
Specific Gravity: 2.68-2.80 (Aquamarine); 3.03-3.25 (Schorl).
Crystal System: Hexagonal (Aquamarine); Trigonal (Schorl).
Color: Blue to blue-green (Aquamarine) with opaque black (Schorl) inclusions.
Luster: Vitreous.
Transparency: Transparent to translucent (Aquamarine); Opaque (Schorl).
Fracture: Conchoidal to uneven (Aquamarine); Uneven to conchoidal (Schorl).
Cleavage: Imperfect basal {0001} (Aquamarine); None distinct (Schorl).
Composition: Beryllium aluminum silicate (Aquamarine); Sodium iron aluminum borosilicate (Schorl).

Quick Check

Color: Blue to blue-green (aquamarine) with black (schorl) inclusions.
Luster: Vitreous (glassy).
Streak: White (aquamarine); black (schorl, though typically not streaked due to hardness).

Physical Characteristics

Crystal Habit: Aquamarine: Prismatic, typically hexagonal, often with striations parallel to the c-axis. Schorl: Prismatic, acicular, columnar, often with vertical striations, sometimes radiating.
Cleavage Type: Aquamarine: Imperfect basal {0001}. Schorl: None distinct.
Fracture Type: Aquamarine: Conchoidal to uneven. Schorl: Uneven to conchoidal.
Tenacity: Brittle for both aquamarine and schorl.
Luster Type: Vitreous (glassy) for both aquamarine and schorl.

Formation

Aquamarine, a variety of beryl, forms in granitic pegmatites, hydrothermal veins, and certain metamorphic rocks. Schorl, a common black tourmaline, also forms in similar environments, particularly in granitic pegmatites and high-temperature metamorphic rocks. The inclusions occur when schorl crystals grow within the beryl crystal during its formation, indicating co-crystallization or sequential growth within the same geological environment.

Usage

Primarily a collector's mineral and a gemstone, though the inclusions often reduce its value as a faceted gem. Specimens with well-formed or aesthetically pleasing schorl inclusions are highly prized by mineral collectors. It is not used in industrial applications due to the inclusions and its primary value as a gemstone/specimen.

Age Distribution

Typically found in pegmatites and granitic rocks, which can range from Precambrian to Cenozoic, with many significant deposits being Mesozoic or Cenozoic.

Where to Find

Minas Gerais, Brazil

A world-renowned source for high-quality aquamarine and schorl. Many pegmatite mines in this region produce excellent specimens of aquamarine with schorl inclusions.

Pakistan (Gilgit-Baltistan)

Known for producing fine aquamarine crystals, often with associated minerals including schorl.

Afghanistan (Nuristan Province)

Pegmatite deposits yield aquamarine and tourmaline, sometimes found together as inclusions.

Nigeria

Certain pegmatite occurrences in Nigeria have produced aquamarine with various inclusions, including schorl.

Madagascar

Pegmatite fields in Madagascar are known for diverse mineralogy, including beryl and tourmaline, leading to occurrences of included aquamarine.

Finding Tips

Target Pegmatite Environments

Focus your search on granitic pegmatites, especially those known for producing beryl and tourmaline. Look for areas with exposed pegmatite dikes or veins.

Look for Associated Minerals

Aquamarine and schorl are often found with quartz, feldspar (orthoclase, albite), muscovite, and sometimes other pegmatite minerals like lepidolite or garnet.

Examine Crystal Habits

Identify hexagonal beryl crystals and look for black, prismatic or needle-like inclusions within them. The contrast in color is a key indicator.

Check for Transparency

While the aquamarine may be transparent to translucent, the schorl inclusions will be opaque black. Use a strong light source to examine the interior of beryl crystals for inclusions.

Safety Precautions

When collecting in pegmatite environments, be aware of unstable rock formations. Beryl contains beryllium, which can be toxic if inhaled as dust. Always wear appropriate personal protective equipment (PPE), including dust masks, eye protection, and gloves, especially when breaking or processing specimens. Avoid ingesting any mineral dust. Wash hands thoroughly after handling specimens.

Similar Rocks

Clear Quartz with Tourmaline Inclusions

SiO2 (Quartz) with Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)4 (Schorl inclusions)

Also known as: Tourmalinated Quartz

Emerald with Inclusions

Be3Al2Si6O18 (Beryl variety)

Also known as: Included Emerald

Beryl (general) with Inclusions

Be3Al2Si6O18

Also known as: Included Beryl

Scientific Classification

Mineral Class: Silicates
Group: Cyclosilicates (Beryl); Cyclosilicates (Tourmaline Group)
Crystal System: Hexagonal (Beryl); Trigonal (Tourmaline)
Chemical Formula: Be3Al2Si6O18 (Beryl) with Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)4 (Schorl)
Composition: Beryllium aluminum silicate (Beryl); Sodium iron aluminum borosilicate (Schorl)

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