Rhodonite

The specimen appears to be a rough, massive pink-to-salmon material with cream-white areas and dark gray to black veining. Rhodonite has a Mohs hardness of about 5.5–6.5, vitreous to pearly luster, imperfect cleavage, and a triclinic crystal structure. Its pink color is caused mainly by manganese. The dark veins are commonly manganese oxides such as pyrolusite or manganese-rich alteration products. Specific gravity is typically about 3.4–3.7. Identification from this photograph is provisional because the specimen is somewhat out of focus and may also be a rhodonite-bearing rock or pink feldspar-rich material.

Rhodonite forms when manganese-rich fluids or sediments are altered during metamorphism, commonly in contact-metamorphic and hydrothermal environments. It can occur in manganese deposits with quartz, calcite, garnet, and manganese oxides. The age depends on the deposit; rhodonite occurs in rocks ranging from Precambrian to much younger geological ages. This specimen is not classifiable as purely igneous, sedimentary, or metamorphic from the image alone; it is best described as a manganese-bearing mineral specimen, possibly from a metamorphic or hydrothermal deposit.

Attractive material is cut and polished for cabochons, carvings, ornamental stones, beads, and small display specimens. Rhodonite is also collected as a mineral. It has little major industrial use, although manganese minerals are important in steelmaking and batteries. The pictured rough piece is more likely a decorative or collecting specimen than gem-quality material.

Rhodonite is often recognized by its characteristic rose-pink color crossed by black manganese-oxide veining. It is sometimes confused with rhodochrosite, pink calcite, rose quartz, pink feldspar, and pink granite. Unlike calcite, rhodonite does not effervesce readily in dilute hydrochloric acid, and it is harder than calcite. Some rhodonite specimens can be translucent at thin edges and take a good polish.

Likely field clues are the salmon-pink massive color, dark or black branching veins, moderate hardness, and relatively high density. A steel knife should leave little or no scratch if the material is rhodonite, while a quartz crystal or piece of glass should scratch it. A streak test on an unimportant edge, hardness testing, acid testing, and examination under magnification would help distinguish it from pink calcite or feldspar. Common sources include Australia, Russia, Sweden, Brazil, Peru, South Africa, and the United States, especially Massachusetts and New Jersey. The exact identity and locality cannot be confirmed from the photograph alone.