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 silverwhite 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