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Acanthite - Ag2S -Acanthite forms splendent black flat bladed crystals that resemble feathers or leaves. This mineral forms exclusively on or near wire silver within the siderite vugs.
Anglesite - PbSO4 - Anglesite at the Mascot typically occurs as lustrous colorless short or elongated prismatic crystals with a rhombic cross-section. Equant anglesite crystals of complex crystal morphology have been found less frequently. Typically, anglesite is found within rusty patches in the mixed sulfide assemblage. It also has been observed within the siderite vugs growing upon chalcopyrite crystals. Mascot anglesite crystals are usually quite small, less than .5mm in length.
Aragonite (?) - CaCO3 - Chalky-white tapering prismatic crystals to .5cm growing in jack-straw fashion upon the surface of dump rocks are believed to be aragonite. These effervesce strongly in acid confirming the mineral is a carbonate.
Arsenopyrite - FeAsS - Arsenopyrite crystals are rare at the Mascot. They have been found as diamond-shaped striated crystals to 1mm within the mixed sulfides. It is possible that massive arsenopyrite occurs more commonly, as it may be difficult to distinguish it from massive pyrite.
Aurichalcite (?) - (Zn,Cu)5(CO3)2(OH)6 - An acicular mineral that forms as tufts of needles and as fibrous mats is believed to be aurichalcite. An SEM EDS trace does show copper with some zinc. The color of the mineral is a robin's egg blue to a pastel blue-green. It is uncommon at the Mascot.
Brochantite - CuSO4(OH)6 - Brochantite is moderately abundant, usually as a druse of minute crystals often associated with chalcopyrite- bearing ore. Larger crystals (still less than .5mm in size) are blocky pseudo-orthorhombic in habit with a rectangular or diamond-shaped cross section. Brochantite is a dark emerald green color and is usually gemmy.
Cerussite - PbCO3 - Cerussite displays a number of habits at the Mascot. Opaque white thin prismatic crystals are sometimes found, usually associated with malachite. Cerussite can also be in the form of very thin tabular plates. Bladed cerussite is perhaps the most common habit at this locality especially within the siderite vugs where it often is found associated with chalcopyrite. The cerussite is white to yellow in color usually with a characteristic oily luster. Twinning is common. Very clear lustrous prismatic cerussite is sometimes noted within the siderite matrix. These crystals,at quick glance, can resemble quartz crystals. Mascot cerussite crystals are usually less than 1mm in size.
Chalcopyrite - CuFeS2 - Primary chalcopyrite is common and is usually associated with other sulfides in massive form. Within the siderite vugs, however, sharp sphenoidal crystals of secondary chalcopyrite to .5cm are commonly found. These crystals are sometimes a clean brassy color, but usually they are tarnished or coated. Associated minerals include silver, cerussite and rarely anglesite. This author is not aware of a better locality in New Hampshire to find chalcopyrite crystals.
Chamosite / Ortho-chamosite- (Fe,Mg,Al)6(Si,Al)4O10(OH,O)8 - SEM EDS analysis of a mineral that forms olive-green botryoidal crystals shows it is an iron-rich member of the chlorite group of minerals. The individual botryoidal crystals are under .5mm across, but they sometimes form into dense mats that line seams in fine-grained siderite.
Cuprite - Cu3O - Cuprite crystals usually are found within rusty patches of the mixed sulfide assemblage. The cuprite is a deep ruby red in color with the most common crystal habit being the octahedron. The crystals are usually very tiny, perhaps .1mm in size. A few larger ones have been found, but even these are smaller than .5mm. Chalcopyrite is the most common associated mineral. Cuprite has not been found to date within the siderite cavities.
Galena - PbS - Galena is common as embedded crystals, veins and stringers. Free growing crystals are rare at this locality.
Con't. on page 7
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