Rutherfordine

Rutherfordine is a mineral containing almost pure uranyl carbonate (UO₂CO₃). It crystallizes in the orthorhombic system in translucent lathlike, elongated, commonly radiating in fibrous, and in pulverulent, earthy to very fine-grained dense masses. It has a specific gravity of 5.7 and exhibits two directions of cleavage. It appears as brownish, brownish yellow, white, light brown orange, or light yellow fluorescent encrustations. It is also known as diderichite.

Rutherfordine
General
Category	Carbonate mineral
Formula (repeating unit)	UO2CO3
IMA symbol	Rfd[1]
Strunz classification	5.EB.05
Crystal system	Orthorhombic
Crystal class	Pyramidal (mm2) H–M Symbol: (mm2)
Space group	Imm2
Unit cell	a = 4.840 Å, b = 9.273 Å c = 4.298 Å; Z = 2
Identification
Colour	Brownish, brownish yellow, white, light brown orange, or light yellow
Crystal habit	Crystals are Lathlike, elongated crystals commonly radiating, fibrous, matted; earthy to very fine-grained masses.
Cleavage	perfect on {010}, good on {001}
Lustre	Silky, dull
Streak	Yellow
Diaphaneity	Transparent
Specific gravity	5.7
Optical properties	Biaxial (+)
Refractive index	nα = 1.700 - 1.723 nβ = 1.716 - 1.730 nγ = 1.755 - 1.795
Birefringence	δ = 0.055 - 0.072
Pleochroism	Visible X= colorless, Y= pale yellow, Z= pale greenish yellow
2V angle	Calculated: 53°
Other characteristics	Radioactive
References	[2][3][4]

It was first described in 1906 for an occurrence in the Morogoro Region of Tanzania. It was named for Ernest Rutherford. It has been reported in the Democratic Republic of Congo, the Northern Territory of Australia and a variety of locations worldwide.[3]

It occurs as a secondary mineral as a weathering product of uraninite. In addition to uraninite it occurs associated with the rare minerals becquerelite, masuyite, schoepite, kasolite, curite, boltwoodite, vandendriesscheite, billietite, metatorbernite, fourmarierite, studtite and sklodowskite.[2] It forms under acidic to neutral pH and is the only known mineral that contains only uranyl and carbonate.