Petersenite-(Ce) (Type Locality)
Na₄(REE)₂(CO₃)₅

     Petersenite-(Ce), formerly UK #100 and a member of the burbankite, is a rare species at MSH.

PHYSICAL CHARACTERISTICS:

Color varies from gray, pink, yellow, mauve, colorless and
   brownish-yellow.
Luster is vitreous.
Diaphaneity is translucent to transparent.
Crystal System is monoclinic; P2₁.
Crystal Habits include striated hexagonal prismatic crystals, prismatic
   inclusions and acicular crystals to 7mm
Cleavage is not apparent.
Fracture is conchoidal.
Hardness is ~3.
Specific Gravity is approximately 3.69 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, astrophyllite, calcio-
   burbankite, catapleiite, epididymite, eudialyte, gaidonnayite, lanthanite,
   manganneptunite, manganotychite, microcline, reederite, rhodochrosite,
   sérandite, shomiokite, shortite, siderite, trona and UK #91.
Distinguishing Features: Crystal habits and colors.
Origin: Named in 1994 after Ole Valdemar Petersen (b.1939), Danish
   museum curator.

CLASSIFICATION:

REFERENCES:
CanMin 32:405-414 (1994), Dana 8:460-461 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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