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The Mineral serandite

Serandite, Rhodochrosite, & Analcime

Serandite is a very rare mineral except at one locality, where it forms in large, well-shaped crystals. It is probably the most famous mineral from the unique pegmatite occurrence of Mont Saint Hilaire, Quebec. Serandite forms very attractive pink and salmon-colored crystals, and its frequent association with Analcime is a popular combination. Many minerals form pseudomorphs after Serandite, completely replacing the Serandite but preserving its original shape.

Chemical Formula

Na(Mn,Ca)₂Si₃O₈(OH)

Color

Pink, orange, red, tan, and brown. May oxidize brown or black upon exposure to air.

Crystal System

Triclinic

Properties

Streak
White

Hardness
5 - 5.5

Transparency
Transparent to nearly opaque

Specific Gravity
3.2 - 3.4

Luster
Vitreous, greasy

Cleavage
1,2 - pinacoidal, similar to that of the pyroxene minerals

Fracture
Uneven, splintery

Tenacity
Brittle

Crystal Habits

Occurs in prismatic and tabular crystals. Crystals can be long and slender or short and stubby. Aggregates include bladed, columnar, encrusting, acicular, radiating, and fibrous. Crystals may sometimes have etchings or small holes.

Additional Information

Composition
Basic sodium manganese calcium silicate

In Group
Silicates; Inosilicates

Striking Features
Color, locality, and mineral associations

Environment
In alkali-rich nepheline syenite pegmatites.

Rock Type
Igneous

Uses

Serandite is well sought after by mineral collectors, and good specimens are very costly and in demand.

Noteworthy Localities

Small amounts of Serandite were found on Rouma Island, Los Islands, Guinea; the Shkatulka pegmatite in the Umbozero mine, Kola Peninsula, Russia; the Gem Mine, San Benito Co., California; and in the Demix-Varennes quarry, Saint-Amable, Quebec (Canada). However, the finest examples of this mineral occur in relative abundance in Mont Saint Hilaire, Quebec (Canada) which is the only significant source of this mineral. Serandite is one of the minerals responsible for making the unique locality of Mont Saint Hilaire famous.