Mineral Specimen #4346 Ankerite and Druze Quartz on Sphalerite variety: Marmatite
Nentsberry Haggs Mine, Nent Valley, Alston Moor District, Cumbria, England
7.7 x 6 x 5.3 cm
1800s,. Ex. H. R. McBroom, purchased from Sam Weller, 1985
This specimen was labeled by Sam Weller as being Dolomite. The species is not listed on mindat for the location; however, Ankerite is. I have taken the liberty of identifying it as Ankerite, since it does by sight, look more like Ankerite. That being said, the two minerals are very closely related and do appear quite similar. The Ankerite/Dolomite is present in two forms, as blocky curved single crystals and as spherical aggregates of smaller bladed crystals. The best of the spherical aggregates are at one end of the specimen and rest on a bed of white druze Quartz. The Ankerite/Dolomite has also grown on underlying black, iron rich Sphalerite crystals (variety Marmatite). The luster of the Ankerite varies from dull. on the spherical aggregates. to glossy on some of the curved crystals on the side of the specimen opposite of where the spherical aggregates are. The Sphalerite has a good metallic luster and the druze Quartz is sparkly.
The specimen is in very good condition with the exception of one place near one end where a Sphelerite crystals broken off (near the top in the first two photos).
This mineral is also found in the following galleries: Minerals From Europe | Carbonates | Sulfides and Sulfosalts | Minerals Priced Between 100 and 199 Dollars