NON-SILICATES

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)

• 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

• 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

• 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 colored with 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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)

• black and occurs often in botryoidal form• goethite

• black and often oxidizes to limonite (yellow)• bauxite

• recognized by its pisolitic form—most important ore of Al

• 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

• Carbonates• The remaining non silicate classes 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 strong effervescence with cold HCl in a solid non powered form

• magnesite• prominent rhombohedral cleavage but rare and

usually white and very fine grained

• 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

• 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

• 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 and effervescence 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

• 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

• 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

• 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

• 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 earth phosphate with high S.G. and main source of

Th and other rare earth elements

• 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