NON-SILICATES

1. NON-SILICATES

2. Non Silicates • Native Elements • minerals comprised of atoms of only one element • 1. metals • minerals with high heat and electrical conductance, malleability, ductility and a strong metallic bond • Au, Ag, Cu, Pt, etc. • 2. semi metals • minerals with lesser conductivity but more brittle than metals and consist of a mixture of metallic and covalent bond types • Sb, Bi and As • 3. non metals • minerals which are non conductors, are very brittle and soft and have a covalent type of bond • C (graphite), S (sulfur)

3. Sulfides, Arsenides, Sulfarsenides • minerals with strong metallic bond type with a general formula,AmXp, where X is S or As, Sb, Bi and Te and A represents one or more metals • sulfides--S is the only major anion • arsenides--As takes the place of S totally ( NiAs) • sulfarsenides—semimetals take place of S in part (FeAsS) • many of these minerals are known as “primary minerals” or those formed from hydrothermal solutions with no oxidation during formation • examples are: • chalcocite—resembles enargite but has no cleavage • bornite—peacock ore—displays a tarnish and can resemble covellite but does not have cleavage • galena –very high specific gravity with cubic cleavage and the only source of lead

4. sphalerite • comprised of Fe and Zn • resinous to adamantine • yellowish to deep red(ruby ore) to black(jack) indicating a progressively higher Fe content • used as a geothermal mineral—the higher the Fe content, the higher the temperature of formation • most important ore of Zn and an important source of Cd • leaves a rotten egg smell when rubbed on a porcelain scratch plate • chalcopyrite • distinguished from pyrite in that it has no cleavage and is softer than glass • distinguished from millerite in that it has no radiating crystal habit • distinguished from pyrrhotite in that it is not magnetic • “ “ marcasite in that it has no cockscomb structure

5. pyrrhotite • magnetic caused by omission solid solution and a defect structure caused by an Fe deficiency with respect to S in the formula • niccoline (niccolite) • red-brass coloredwith a high specific gravity • millerite • hair like radiating crystal habit • pentlandite • resembles pyrrhotite but not magnetic • principle ore of Ni • covellite • also known as peacock ore, with special iridescence • excellent cleavage resembling that of mica • indigo color

6. cinnabar • red, high specific gravity with prominent cleavage • most important ore of Hg • realgar • red and associated with orpiment • orpiment • yellow and distinguished from S by its prominent cleavage • pyrite • harder than chalcopyrite • occurs often in cubic cleavage form with striations • most common sulfide minerals • commonly known as fool’s gold • marcasite • a polymorph with pyrite • differs from pyrite by the presence of the cockscomb structure

7. molybdenite • distinguished from graphite by a higher specific gravity and more bluish tone • principal ore of Mo • arsenopyrite • distinguished from marcasite by its somewhat silver-white color • principal source of As

8. Sulfosalts • have general formula, AmBnXp where A can be Ag, Cu, Pb and B can be As, Sb,Bi and X is S • the semimetals act as cations in the sulfosalts as compared to anions in the sulfarsenides and arsenides • an example is: • enargite • distinguished from chalcocite by its prominent cleavage • Oxides • bond type is primarily ionic which results in part to a greater hardness displayed by these compared to others previously discussed • examples are: • cuprite • in various shades of red

9. zincite • red and occurs often with franklinite • Hematite group • isostructural group—6 O bonded to each cation and 4 anions bonded to each cation (e.v. of bond = ½) • examples are: • corundum • hardness = 9 • sapphires (blue) and rubies (red) are important gem stone varieties • hematite • occurs often as oolitic hematite (non metallic luster) or specularite or massive hematite (both metallic luster) • most important ore of iron • ilmenite • distingushed from magnetite from lack of strong magnetism • The major source of Ti

10. Rutile group • isostructural group with 6 O around each cation and 3 cations around each O • examples are: • rutile • much lower S.G. than cassiterite • adamantine luster and reddish color • pyrolustite • low hardness and leaves a black streak on paper • most important Mn ore • cassiterite • very high S.G. • principal ore of Sn

11. Spinel group • isostructural group—first cation in formula is +2 and second is +3 • examples are: • magnetite • very magnetic • chromite • massive to granular • distinguished from magnetite by lack of magnetism • the only abundant ore of Cr • franklinite • distinguished from magnetite by lack of strong magnetism • is abundantly associated with zincite

12. Hydroxides • examples are: • brucite • distinguished from talc by a greater hardness and lack of a strong greasy feel • manganite • distinguished from pyrolusite and other black mineral by its brown streak • often occurs in prismatic crystals • romanechite (psilomelane) • blackand occurs often in botryoidal form • goethite • black and often oxidizes to limonite (yellow) • bauxite • recognized by its pisolitic form—most important ore of Al

13. Halides • consists of minerals with a halogen anion • examples are: • halite • distinguished by its cubic cleavage and salty taste which is less bitter than taste of sylvite • cryolite • fluorite • often found in cubes and in various colors • has distinct octahedral cleavage • is an important source of F in the production of HF

14. Carbonates • The remainingnon silicateclasses are comprised of minerals each combined with a meso-or aniso and isodesmic bond • Calcite group • isostructural group 6 O around each major cation, 3 O around C and 1 C and 2 other major cations around each O • examples are: • calcite • prominent rhombohedral cleavage and often found as rhombohedron or scalenohedron(dog tooth) forms • distinguished from other minerals by strongeffervescence with cold HCl in a solid non powered form • magnesite • prominent rhombohedral cleavage but rare and usually white and very fine grained

15. siderite • prominent rhombohedral cleavage with curved faces • distinguished from other carbonates by its light to dark brown color and from sphalerite by its type of cleavage and lack of smell of rotten eggs on a streak plate • rhodochrosite • prominent rhombohedral cleavage with curved faces and pink color • smithsonite • blue-green in color and botryoidal or stalactitic in form • Aragonite group • isostructural group with 9 Oaround each major cation, 3 O around each C, and 1 C and 3 major cations around each O

16. aragonite • polymorphic with calcite • distinguished from calcite by the lack of rhombohedral cleavage and from witherite and strontionate by its much lower S.G. • witherite • high S.G. • distinguished from barite by its effervescence in cold HCl in powered form • Dolomite group • isostructural group similar to the calcite group • example is: • dolomite • often displays curved rhombohedral cleavage • effervesces in HCl in power form only

17. Hydrous Carbonate group • examples are: • malachite • distinguished by its bright green color and botryoidal form • effervesces with cold dilute HCl yeilding a green solution • azurite • distinguished by its azure blue color andeffervescence with cold HCl yielding a blue solution • Borates • there is a polmerization of the basic structural units as in the silicates because of the presence of the mesodesmic bond • borates are the source of borax and B

18. examples are: • kernite • characterized by its long splintery cleavage fragments and slow solubility in cold water • can resemble gypsum but is harder and cannot be scratched by the fingernail • borax • characterized by its crystals and its low hardness resulting in powdery form • easily soluble in cold water • colemanite • commonly found in short prismatic crystals

19. Sulfates • Barite group • isostructural group with 12 O around each major cation, 4 O around each S, and 1 S and 3 major cations around each O • an example is: • barite • distinguished by its prominent cleavage, high S.G. and often by the special crystal forms as bladed barite, clear barite,rose barite and a black barite • chief source of Ba • anhydrite • not isostructural with barite---8 O around each Ca, 4 O around each S and 1 S and only 2 Ca around each O • 2 directional 90 degree cleavage

20. Hydrous Sulfate group • examples are: • gypsum • characterized by its low hardness (2) and 3 cleavage directions • can occur in several forms as bladed gypsum, selenite (clear),satin spar and massive or alabaster • alunite • Tungstates • wolframite group is an isostructural group • an example is: • wolframite • distinguished from other minerals by its black color, one directional cleavage and high S.G. • an important ore of W

21. Molybdates • an example is: • wulfenite • characterized by its orange-yellow color, high S.G. and tabular (tetragonal) crystals • Vanadates • an example is: • vanadinite • characterized by its ruby red to orange red color, resinous luster and high S.G. • Phosphates • examples are: • monazite • rare earthphosphate with high S.G. and main source of Th and other rare earth elements

22. apatite • green, red and yellow apatite are varieties • amblygonite • distinguished from sodic plagioclase by the lack of striations • wavelite • commonly in radiating crystal form and green in color • turquoise • distinguished by its color and harder than chrysocolla