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Hiortdahlite
(Ca,Na)3(Zr,Ti,Nb)Si2O7(O,OH,F)2

     Hiortdahlite, a member of the cuspidine-wöhlerite group, is another rare species at MSH.

PHYSICAL CHARACTERISTICS:

Color is usually yellow to yellow-brown.
Luster is vitreous to greasy.
Diaphaneity is transparent to translucent.
Crystal System is triclinic; P1.
Crystal Habits include tabular crystals, pseudo-tetragonal crystals
   and acicular sprays.
Cleavage {100} and {1-10} are distinct.
Fracture is (??).
Hardness is 5.5 - 6.
Specific Gravity is approximately 3.25 g/cm3.
Streak is yellow.
Associated Minerals include (??).
Distinguishing Features: Crystal habits and streak.
Origin: Named in 1889 after Thorsten Hallager Hiortdahl (1839-1925),
   Norwegian.

CLASSIFICATION:

Dana System
# 56.2.4.7

Strunz Classification
# VIII/C.11-50

REFERENCES:
Dana 8:1164-1165 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
--

AP
--

MX
--

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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