Horváthite-(Y) (Type Locality)
NaY(CO)₃F₂

     Horváthite-(Y) is a very rare REE species from MSH. It is one of already 30+ rare-earth element fluorocarbonates from the locality. It had originally been discovered in 1994 by Steve and Janet Cares (caresite) and designated as UK #104.

PHYSICAL CHARACTERISTICS:

Color is colorless to pale beige.
Luster is vitreous.
Diaphaneity is translucent to transparent.
Crystal System is orthorhombic; Pmcn.
Crystal Habits include stacked plates to 0.3mm and blocky
   aggregates (wagon-wheel) of radiating crystals to 5mm with
   individual striated crystals to 1mm.
Cleavage {100} is very good and {010} is good.
Fracture is uneven.
Hardness is ~ 4.
Specific Gravity is > 3.3 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, astrophyllite, catapleiite,
   dawsonite, genthelvite, microcline, natrolite, rhodochrosite, sérandite,
   siderite, sodalite and tainiolite.
Distinguishing Features: Crystal habit.
Origin: Named in 1997 after Elsa (b. 1947) and László Horváth
   (b. 1937), a husband-wife team dedicated to the collection, study
   and documentation of Mont Saint-Hilaire minerals.

CLASSIFICATION:

REFERENCES:
CanMin 35:743-749 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

Legend