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Pyrite is distinguishable from native gold by its hardness, brittleness and crystal form. Pyrite fractures are very uneven, sometimes conchoidal because it does not cleave along a preferential plane. Native gold nuggets, or glitters, do not break but deform in a ductile way. Pyrite is brittle, gold is malleable.
A framboid is a micromorphological feature common to certain sedimentary minerals, particularly pyrite (FeS 2).The first known use of the term is ascribed to Rust in 1935 and is derived from the French 'framboise', meaning 'raspberry', reflecting the appearance of the structure under magnification.
When grounds rich in pyrite, such as many clays or marls, are excavated for civil engineering works, the strong acidification produced by pyrite oxidation is the powerful driving force triggering TSA because it frees up and mobilizes all the ions needed to attack C-S-H and to form thaumasite (CaSiO 3 ·CaCO 3 ·CaSO 4 · 15H 2 O).
The group is named for its most common member, pyrite (fool's gold), which is sometimes explicitly distinguished from the group's other members as iron pyrite. Pyrrhotite (magnetic pyrite) is magnetic, and is composed of iron and sulfur , but it has a different structure and is not in the pyrite group.
Marcasite reacts more readily than pyrite under conditions of high humidity. The product of this disintegration is iron(II) sulfate and sulfuric acid. The hydrous iron sulfate forms a white powder consisting of the mineral melanterite, FeSO 4 ·7H 2 O. [13] This disintegration of marcasite in mineral collections is known as "pyrite decay".
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A disadvantage of pressure oxidation is that any silver in the feed material will often react to form silver jarosite inside the autoclave, making it difficult and expensive to recover the silver. [1] An example of a mine utilizing this technology is the Pueblo Viejo mine in the Dominican Republic. At Pueblo Viejo, the process is performed by ...