GREENOCKITE
GREENOCKITE Greenockite – CdS – is a rare sulfide. It is the only ore mineral of Cd, but Cd is obtained as a by-product in the mining of Pb, Zn, and Cu. Greenockite was used as a yellow pigment until it was recognized that Cd is very toxic. It is classified in the Wurtzite Group, […]
GUMMITE
GUMMITE “Gummite” is the name given to a mixture of uraninite and secondary uranium minerals of variable composition. This mixture is composed of uraninite remnants mixed with boltwoodite, clarkeite, curite, kasolite, soddyite, and uranophane. Sometimes the material has the appearance and consistency of rubber, and the name comes from this: “Gummi” means rubber in German. […]
GIBBSITE
GIBBSITE Gibbsite – Al(OH)3 -is a very common hydroxide, an important component of soils and one of the minerals that make up laterites and bauxites, which are aluminum ores. Gibbsitic clays are also interesting for the manufacture of refractory materials. Gibbsite, also called hydrargillite, has the polymorphs bayerite, doyleite and nordstrandite and a basic mica […]
GARNIERITE
GARNIERITE Garnierite, an important nickel (NiO) ore, is not a single mineral, but a generic, “umbrella” term for a mixture of varying shades of green of more than six different hydrated phyllosilicates of Ni and Mg. This mixture includes two or more of the following minerals: serpentine, talc, sepiolite, smectite, chlorite, and vermiculite. In addition, […]
GERSDORFFITE
GERSDORFFITE Gersdorffite – NiAsS – is a relatively rare sulfide. It is possible that it was not detected in many occurrences due to its similarity to galena and other ores. Integrates polymetallic ores. It is classified in the Cobaltite Group which, except for cobaltite itself, is made up of rare and extremely rare minerals. It […]
GYPSUM
GYPSUM Gypsum – CaSO4.2H2O – is the most common sulfate, one of the most abundant minerals in evaporite rocks. It is a very important ore for plaster, mineral fillers, fertilizers, and much more. It is classified in the Gypsum Supergroup, being isostructural with ardealite, brushite, and pharmacolite. It can dehydrate to bassanite at high temperatures. […]
GLAUCODOT
GLAUCODOT Glaucodot – (CoFe)AsS – is a quite rare and unusual sulfide, important as a cobalt ore alongside cobaltite, alloclasite, and other cobalt minerals. It is classified within the arsenopyrite group. It may contain nickel. 1. Characteristics Crystal system: Orthorhombic pyramidal. Color: From grayish tin-white to reddish silver-white. Habit: Large, euhedral prismatic crystals. […]
GLAUCONITE
GLAUCONITE Glauconite – (K,Na)(Mg,Fe+2,Fe+3)(Fe+3,Al)(Si,Al)4O10(OH)2 – is a common phyllosilicate in marine sediments and sedimentary rocks. It has no economic importance. For decades it was believed that glauconite and celadonite were the same mineral. Therefore, care must be taken with old samples, which may have the wrong designation. Celadonite may contain Ti, Ca, and P as […]
GRAPHITE
GRAPHITE Graphite – C – a native element, is easy to recognize macroscopically due to its bright gray color, lamellar shape, unctuous feel and being very soft, it get your fingers dirty. It is very similar to molybdenite (MoS2), which it was confused with for a long time. It is not a common mineral; in […]
GRUNERITE
GRUNERITE Grunerite – ☐{Fe22+}{Fe52+}(Si8O22)(OH)2 – is an inosilicate from the Amphibole Group. It is a rarer mineral, with some very specific parageneses. It was mined as “asbestos” in its fibrous form – “amosite” – but the worldwide trend is to end the mining and use of the various minerals considered as “asbestos”. It is classified […]