Worldwide Field Guide

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Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits.

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Barite, chemical formula BaSO4, is a mineral consisting of barium sulfate.

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Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey.

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The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6.

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Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3).

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Celestite has the chemical formula SrSO4 and is a mineral consisting of strontium sulfate. The mineral is also known as Celestine, and is named for its occasional delicate blue color.

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Cerussite, also known as lead carbonate or white lead ore, is a mineral consisting of lead carbonate (PbCO3), and an important ore of lead.

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Dacite is an igneous, volcanic rock.

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In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is the second most stable form of carbon, after graphite; however, the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is specifically renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material synthesized so far.

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Fluorite (also called fluorspar) is a halide mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon.

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Geyserite is a form of opaline silica that is often found around hot springs and geysers.

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Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.

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Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as porphyry. Granites can be pink to dark gray or even black, depending on their chemistry and mineralogy. Outcrops of granite tend to form tors, and rounded massifs. Granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels.

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Halite is the mineral form of sodium chloride, NaCl, commonly known as rock salt. Halite forms isometric crystals. The mineral is typically colorless to yellow, but may also be light blue, dark blue, and pink depending on the amount and type of impurities.

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Hematite is the mineral form of iron(III) oxide (Fe2O3), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum. Hematite and ilmenite form a complete solid solution at temperatures above 950°C.

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Iron is a metallic chemical element with the symbol Fe and atomic number 26. Iron is a group 8 and period 4 element and is therefore classified as a transition metal. Iron and iron alloys (steels) are by far the most common metals and the most common ferromagnetic materials in everyday use.

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Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides. The common chemical name is ferrous-ferric oxide.

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Mimetite is an arsenate mineral which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite.

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Scolecite is a tectosilicate mineral belonging to the zeolite group; a hydrated calcium silicate with chemical formula CaAl2Si3O10·3H2O.

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Sulfur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant, multivalent non-metal. Sulfur, in its native form, is a yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals. It is an essential element for life and is found in two amino acids, cysteine and methionine. Its commercial uses are primarily in fertilizers, but it is also widely used in black gunpowder, matches, insecticides and fungicides.