Earth Materials Lecture 11: Hazardous Minerals Flashcards
How many minerals contain Lead(Pb)?
559
What are the main Lead containing minerals?
Galena – sulphide
anglesite – sulphate
cerussite – carbonate
Mimetite – chloro arsenate
pyromorphite – chloro phosphate
vanadinite – chloro vanadate
Why is lead hazardous?
Heavy metals interfere with cellular activities.
* E.g. Pb substitutes for Zn in porphobilinogen synthase disrupting
heme and so blood production leading to anaemia (Jaffe et al., 2000;
Tanak and Tanaka, 2007; Korolnek and Hamza, 2014).
* Pb affects every organ in the body, especially the nervous system.
Interferes with Vitamin D synthesis and DNA transcription (Wani et al.,
2015).
* Can be stored in teeth and bones but released from bones.
* “No known safe blood lead concentration
How many minerals contain Mercury (Hg)?
103
What are the main Mercury bearing minerals?
Native Hg droplets
cinnabar – sulphide
balkanite – sulphide with Cu, Ag
Calomel – chloride
montroydite – oxide
grumiplucite – sulphide with Bi
Why is Mercury hazardous?
Hg salts are poorly absorbed due to their relative stability and insolubility.
- Corrosive to skin, eyes, gastrointestinal tract; possibly kidney failure if ingested (WHO, 2017).
- Gets into food chain as methylmercury via bacterial activity.
- This form is very readily absorbed and deposited in various tissues.
- Elemental Hg crosses the blood-brain barrier where it causes all manner of ills including mental health problems.
- It attacks the nervous and immune systems
- It alters protein functions; interferes with DNA transcription
How many minerals contain Arsenic (As)?
245
What are the main Arsenic bearing minerals?
Arsenopyrite – sulphide
realgar and orpiment – sulphides
enargite – Cu-As sulphide
Löllingite – Fe arsenide
scorodite – hydrous Fe arsenate
arsenolite - oxide
Why is Arsenic hazardous
Arsenic occurs as AsV (arsenate) and AsIII (arsenite) and is most toxic as the latter because more chemically bioactive and so enters cells more readily (IARC, 2011).
- Stored in the liver, kidneys, heart and lungs with lesser amounts in muscles and neuronal tissues.
- It inhibits 200 enzymes in cellular energy pathways, DNA synthesis and repair (Singh et al., 2011 and refs therein; Pelley, 2012).
- Because arsenate is a structural analogue of phosphate (Pelley, 2012).
- Can be mutagenic when in synergy with other molecules and UV, e.g. skin cancer.
- DNA strand breaks via oxidation; disrupts DNA by converting one amino acid to another; interferes with gene expression etc.
How many minerals contain Antimony (Sb)?
281
What are the main Antimony bearing minerals?
Native Sb
Stibnite – sulphide
jamesonite – sulphide with Fe
Stibiconite – hydrous oxide
kermesite – Sb-S oxide
tetrahedrite – sulphide with Cu
What are the variables and qualities that determine whether a mineral is safe to handle?
- Minerals containing toxic elements.
- Bioaccessibility of those elements.
- Depends on stability and hardness of mineral.
- Native Pb, Hg, As and Sb no-nos, highly toxic. Hg vapour, arsine
gas. - Low hardness minerals can be problematic because of powdered
form and inhaling or ingesting dust. - Do not grind the others!
- Fluorite can be problematic – unbound fluorine.
- Arsenolite high solubility.
- Otherwise, H>2 generally safe but always wash hands after use. Avoid dusts.
How many minerals/radioactive minerals contain Uranium(U)
291
What are the main Uranium bearing minerals?
Uraninite – oxide
pitchblende – oxide
brannerite – U titanite
Fergusonite – YREEsNb oxide
samarskite – YFeNb oxide
betafite – complex oxide Ca, Na, Ti, Nb
List secondary alteration products of radioactive minerals
Autunite - Ca phosphate
torbernite - Cu phosphate
cuprosklodowskite - hydrous Cu-silicate
Uranophane - hydrous Ca-silicate
boltwoodite – hydrous KNa silicate
curite – hydrous Pb oxide
How many minerals/radioactive minerals contain Thorium (Th)
22 to 25 minerals
What are the main Thorium bearing minerals
Thorite – silicate (and coffinite)
thorianite – oxide
ichnusaite – molybdate
Thorutite – hydrous oxide with Ca, Ti
monazite – LREE phosphate
cheralite – Ca-phosphate
Describe the occurance of radioactive minerals
Minor constituents in many rocks.
Various economic deposit types.
3 main ones for uranium:
- Proterozoic unconformity 40%
- Sandstone 29%
- Metasomatic/IOCG 19%
Th from:
- placers 35%
- magmatic 37%
- vein type 24%
Why are radioactive minerals hazardous?
Radiation damage caused by particles and high-energy γ-rays.
Genome damage through DNA strand breaks; DNA mis-repair and mutation leading to cancers.
What are the main Asbestiform minerals/Asbestos minerals?
Chrysotile
Crocidolite – blue asbestos
Amosite – brown asbestos
Anthophyllite
Actinolite
Tremolite (NHM, London)
Asbestos has incredibly small fibres
List and describe Zeolites
Apophyllite
Chabazite
Stilbite
Thomsonite
Mordenite
Mesolite
Okenite
Scolecite
Natrolite
Erionite
Offretite
Cage structure,
82 mineral names in 13 groups
(Coombes et a., 1997).
Adsorption, reversible reactions,
cation exchange capacities,
= agricultural, industrial and medical uses
Many have radiating acicular habit.
Describe the occurances of Asbestiform minerals
Chrysotile, actinolite, tremolite and
anthophyllite from metamorphosed mafic
and ultramafic igneous rocks.
* Tremolite and chrysotile from
metamorphosed impure limestones.
* Crocidolite and amosite from
metamorphosed Precambrian iron
formations.
* Fibrous zeolites in amygdales in basalts.
* Erionite also in felsic volcanic ash.
Why are Asbestiform minerals hazardous
Causes various forms of diseases of lungs, oesophagus and
stomach. Number 1 carcinogens.
* Long lead-in time ~30-40 years or more and no cures, as yet.
* Long legacy from mining – people still dying from mining and
processing, and also from contaminated soils.
Amphibole asbestos more toxic than chrysotile and erionite 1000
times more carcinogenic.
* Toxicity of fibres lies in their habit and chemistry.
* Fe on fibre surface induces reactive oxygen species.
* Chronic inflammation and programmed cell necrosis via several
stages.
* DNA strand breaks, oxidation of bases, lipids, proteins
Tiny fibres are breathed in however cannot be breathed out.
Silicosis
