Becquerelite

Becquerelite is a uranium mineral with the chemical formula: Ca(UO₂)₆O₄(OH)₆·8(H₂O). It is a secondary mineral which contains calcium and is a bright yellow colour. It has a Mohs hardness of about 2.

Becquerelite
Spray of becquerelite crystals with uranophane needles from the old Shinkolobwe mine
General
Category	Oxide mineral
Formula (repeating unit)	Ca(UO2)6O4(OH)6·8(H2O)
IMA symbol	Bqr[1]
Strunz classification	4.GB.10
Crystal system	Orthorhombic
Crystal class	Pyramidal (mm2) H-M symbol: (mm2)
Space group	Pn21a
Unit cell	a = 13.8378 Å, b = 12.3781 Å, c = 14.9238 Å; Z = 4
Identification
Colour	Amber-yellow, golden to lemon-yellow, yellow-orange, brownish yellow
Crystal habit	Tabular prismatic striated crystals exhibiting pseudohexagonal outline; coatings and fine-grained aggregates
Cleavage	Perfect on {001}; imperfect on {101}, {010} and {110}
Tenacity	Brittle
Mohs scale hardness	2.5
Lustre	Adamantine to greasy
Streak	Yellow
Diaphaneity	Transparent
Specific gravity	5.09 - 5.2
Optical properties	Biaxial (-)
Refractive index	nα = 1.725 - 1.735 nβ = 1.815 - 1.825 nγ = 1.825 - 1.830
Birefringence	δ = 0.100
Pleochroism	X = colourless to pale yellow, Y = Z = yellow to deep yellow
2V angle	Measured: 32°
Common impurities	Commonly contains lead
Other characteristics	Radioactive
References	[2][3][4]

It was named after the French physicist Antoine Henri Becquerel (1852–1908), who discovered radioactivity in 1896. Becquerelite contains about 70% uranium by weight.

It is mainly mined in Kasolo of the former Zaire, in the present day Democratic Republic of the Congo.