Humite Locality: Monte Somma , Somma-Vesuvius Complex, Naples Province , Campania , Italy ( Locality at mindat.org ) Size: 5.3 x 4.9 x 2.2 cm. A very well crystallized gem humite measuring about 5mm, perched in a protected vug of matrix, from this important locality! Type Locality. Discovered here in 1813. Ex. American Museum of Natural History, Clarence Bement collection, donated in 1910. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Humite
A magnesium silicate-fluoride of the humite group, first described in 1813 from Vesuvius's ejected blocks and named for Abraham Hume.
Intro adapted from Wikipedia (CC BY-SA).
Humite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mg₇(SiO₄)₃F₂.
It crystallizes in the orthorhombic crystal system (space group Pbnm). It is a member of the Humite structural group.
Key properties: Mohs hardness 6; specific gravity 3.2–3.32; Vitreous luster; refractive index 1.639; optically biaxial.
IMA symbol Hu, grandfathered status — known before the IMA’s founding, named in 1813.
is typically found in contact metamorphic zones in limestones and dolostones in association with felsic, or more rarely, alkalic plutonic rocks, especially where metasomatism has introduced Fe, B, and F.
It is found associated with Grossular, wollastonite, forsterite, monticellite, cuspidine, fluoborite, ludwigite, spinel, brucite, calcite, dolomite, serpentine, diopside, corundum.
The name commemorates Sir Abraham Hume (1749–1838), English connoisseur and collector of works of art, gems, and minerals. All rights reserved. No part of this publication may be reproduced.