Metamorphic Rock (composed of multiple minerals)

Ruby in Zoisite

Ruby (α-Al2O3) embedded in Zoisite (Ca2Al3(SiO4)3(OH)) with some Hornblende

Hardness varies: Ruby is 9 on Mohs scale, Zoisite is 6-7. Color: Ruby is pink to dark red, Zoisite is typically green, sometimes with black specks of hornblende. Luster: Vitreous to pearly. Crystal Structure: Ruby forms hexagonal crystals; Zoisite forms orthorhombic crystals. Cleavage: Ruby has no cleavage;…

Luster: Vitreous to pearly

Identified September 27, 2025More metamorphic rock (composed of multiple minerals) →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Ruby in Zoisite is a metamorphic rock formed by regional metamorphism of igneous and sedimentary rocks rich in aluminum and calcium. The ruby crystals form within the zoisite matrix under high pressure and temperature conditions. It can be found in some of the oldest parts of the Earth's continental crust. Its geological age can vary, dating back millions of years depending on the specific deposit.

Uses & applications

Primarily used as an ornamental stone and for carving due to its attractive color contrast. It's popular in jewelry for cabochons, beads (like in the image), and tumbled stones. It is not typically used in industry or construction.

Geological facts

Also known as Anyolite, named after a Masai word meaning 'green' (anyoli). Although the ruby in this combination is opaque and not gem-grade, its vibrant color against the green zoisite makes it a striking gemstone. It's often associated with promoting passion, vitality, and spiritual growth.

Field identification & locations

In the field, it's identified by its distinct color combination: opaque pink to red ruby crystals embedded in a dark to bright green zoisite matrix. Black amphibole (hornblende) can also be present. It is most commonly found in Tanzania, particularly the Longido mining district. Collectors should look for vibrant colors and well-defined ruby crystals within the zoisite.

Other metamorphic rock (composed of multiple minerals) specimens

See all

Given the appearance, it's likely a fragment of an igneous or metamorphic rock composed of multiple minerals. Without specific diagnostic features, it's difficult to give a common name other than 'crystalline rock fragment'. If pressed to guess based on the granular, somewhat light and dark speckled appearance, it could be a fragment of granite or a related intrusive igneous rock.

As a rock fragment, it does not have a single scientific mineral name; rather, it's a piece of a rock which is a combination of minerals. If it were granite, its main mineral composition would be quartz (SiO2), feldspar (e.g., KAlSi3O8 - orthoclase, (Na,Ca)(Al,Si)4O8 - plagioclase), and mica (e.g., KAl2(AlSi3O10)(OH)2 - muscovite or K(Mg,Fe)3AlSi3O10(OH)2 - biotite), among others.

Mineral, possibly rock fragment containing a mineral

Lapis Lazuli

Na8[Al6Si6O24]n(S,Cl,SO4,OH)2

metamorphic

Lapis Lazuli (Tumbled Specimen)

Lapis Lazuli (Aggregate rock containing Lazurite: (Na,Ca)8(AlSiO4)6(SO4,S,Cl)2)

metamorphic

Lapis Lazuli

Lazurite (primary mineral component), (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

metamorphic

Lapis Lazuli

Lapis Lazuli (Complex silicate rock containing Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite)

metamorphic

Lapis Lazuli (polished cabochon)

Lazurite-rich metamorphic rock (approx. Na6Ca2Al6Si6O24(SO4,S,Cl)2)

metamorphic