Hungchaoite occurs with ginorite, mcallisterite, sborgite, sassolite, nobleite, ulexite, and, where gypsum and ulexite are abundant, with kurnakovite, inderite, and mcallisterite in surficial matrix as products from weathered colemanite and priceite veins in late Tertiary rocks.

Hungchaoite is triclinic, space group P1; a = 8.811(1), b = 10.644(2), с = 7.888(1)A; α = 103°23(1)′, β = 108°35(1)′, γ = 97°09(1)′ unit-cell volume 666.2(1)A3; Z = 2[MgO·4B2O3·9H2O]. Euhedral, tabular {100} to equant, colorless, untwinned crystals, up to 0.5 mm, show 17 forms. The strongest lines in the X-ray powder pattern are, in A: 6.71(100), 3.356(92), 5.36(85), 4.093(78), 4.079(64), and 7.14(59).

Hungchaoite is optically (−): α = 1.445(2),β = 1.485(2), γ = 1.490(2) (Na light); 2Vα = 15(4)°; r < υ, distinct; X∧ a = +28°, Z∧ b = +37°, Y∧ c = −66°. Good {111} and {111}and imperfect {010} cleavages. Hardness 2½. G (meas) 1.706(5), ρ (calc) 1.705 g cm−3.

Hungchaoite is metastable with respect to inderite and mcallisterite in solution. Dehydration data are given.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.