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Davidite-(La)
Davidite-(La) from Kazakhstan
General
Category	Oxide minerals
Formula (repeating unit)	(La,Ce,Ca)(Y,U)(Ti,Fe ) 20O 38
IMA symbol	Dvd-La
Strunz classification	4.CC.40
Crystal system	Trigonal
Crystal class	Rhombohedral (3) H-M symbol: (3)
Space group	R3
Unit cell	a = 10.376, c = 20.91 ; Z = 3
Identification
Color	Black
Fracture	Subconchoidal to uneven
Tenacity	Brittle
Mohs scale hardness	6
Luster	Vitreous
Diaphaneity	Opaque, translucent in very thin fragments
Specific gravity	4.33 to 4.48
Alters to	Metamict
Other characteristics	Radioactive
References

Davidite is a rare earth oxide mineral with chemical end members Lanthanum (La) and Cerium (Ce). It exists in two forms:

• Davidite-(La) (La,Ce,Ca)(Y,U)(Ti,Fe
  )
  ₂₀O
  ₃₈ discovered at Radium Hill mine, South Australia in 1906 and named by Douglas Mawson for Australian geologist Tannatt William Edgeworth David (1858-1934).
• Davidite-(Ce) (Ce,La)(Y,U)(Ti,Fe
  )
  ₂₀O
  ₃₈ first described in 1960 from Vemork, Iveland, Norway.

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. "Davidite-(La) Mineral Data".
3. Davidite-La in Handbook of Mineralogy
4. Davidite-La on Mindat
5. Davidite-(La) on Webmineral
6. Davidite-(Ce) on Webmineral
7. Branagan, D.F. (2005): T.W. Edgeworth David: A Life: Geologist, Adventurer and "Knight in the Old Brown Hat", National Library of Australia, Canberra, p. 471. ISBN 0 642 10791 2

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