Infrared reflectivity of carbonate, sulfate, nitrate and silicate familie

Hovis, W. A., Jr.

English

NASA Technical Reports Server

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INFRARED REFLECTIVITY OF SOME COMMON MINERALS 
The author is with NASA, Goddatd Space Flight Center 
Greenbelt, Maryland 
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CATEGORY) 
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https://ntrs.nasa.gov/search.jsp?R=19660020045 2020-03-24T03:19:23+00:00Z
ABSTRACT 
Infrared refiectivixies or' minerals of :lie ~arbiii%itz, su l f a t e ,  
nitrate and s i l icate  families exhibit spectral features that can 
5e detected i n  reflection from surface minerals. These features could 
be used to identify such minerals from infrared reflection 
of the moon and some planets  and could also be a source of confusion 
i n  interpretation of atm~spheric spectra. 
spectra 
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I '  I NDR ODUCTION 
The infrared refiection spectrum of minerais has been iiivestlgated 
by a number of people though the work was mainly concerned with 
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I marerials of npticel interest, The recent bibliography by McCarthy(1) 
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contains references to a large number of these measurements. 
recently Rea et a1 (2) investigated the infrared reflectivity of both 
More 
organic and inorganic materials in an attempt to explain features in 
the reflection of Mars. The availability of the infrared total 
reflectance attachment described by White ( 3 )  for the Cary 90 double 
* 
beam spectrometer has made tot81 reflectance measurements beyond 2.5 
microns more readily available 8nd has stimulated the measurements 
reported here. 
EXPERIMENTAL PROCEIKTRE 
t 
- .  The total reflectivity for all specimens was measured with a 6 
Beckman DK 2A double beam spectrometer equipped with a total 
reflectance attachment from 0.5 to 2.5 microns. From 2.5 to 6 
microns measurements were made with the Cary 90 mentioned previously. 
Specimens identified by their chemical name were reagent grade chemicals, 
natural specimens were collected as described in the discussion of 
each specimen. 
PURE MATERIALS 
Carbonates: Carbonates are abundant in the surface mineral cover of 
Calcite or CaC03 is the most abundant occurring as limestone, Earth. 
chalk, as cementing material in sedimentary rocks and in the shells of 
. 
the hard shelled marine organisms. 
granuiar caleiiim carbonate and Fig. 2 the reflectivity of sodium carbonate. 
A number of strong spectral features are seen particularly near 3.5 and 
4.0 microns. 
Figure 1 shows the reflectivity of 
Sulfates: Hydrous calcium sulfate or gypsum is found extensively in 
sedimentary deposits and is normally the first salt deposited in the 
evaporation of sea water. 
2 H20. 
feature at 2.7 to 3 microns is due to water of hydration. 
Figure 3 shows the reflectivity of Ca SO4. 
As with the carbonates numerous strong features are seen. The 
NLtrates: Nitrates are norinally found in arid regions of the Earth, 
the only significant deposits occurring in Chile. 
of sodium and potassium nitrate are shown in Figures 4 and 5 .  
The reflectivities 
Again a - 
number of strong features are observed especially in the 3 to 4 micron region. 
$ 
! - .  Salt: Sodium chloride is widely distributed occurring in extensive I j 
beds following evaporation by enclosed bodies of water. 
of granular sodiu;; chloride is shown in Figure 6. 
1.46, 1.96 and 2.9 microns are due to water of hydration. 
The reflectivity 
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T'ne features at 
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I Silica: Figure 7 shows the reflectivity of a silica sand of high 1 
purity gotten by washing and sizing natural sand. Some water of hydracion 
is present as evidenced by the Eeature at 2.9 microns. The features from 
3.7 to 5 microns are characteristic of natural crystal quartz. While 
synthetic quartz has features at the same wavelengths they are not as 
detailed artd the double features such as the one centered around 4.7 
microns are blended into one. 
of synthetic quartz at longer wavelengths also show this effect since 
The restrahlen or residual ray features 
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1 . .-- . . . . -. . . - - 
n a t u a l  q u a r t z  i s  b i r e f r i n g e n t  afid s y n t h e t i c  q u a r t z  i s  z o t .  This  
i n d i c a t e s  a r e l a t i o n s h i p  berween ihe w e l l  known r e s i d u a l  r a y  f e a t u r e s  
a t  longe r  wavelengths and t h e  f e a r u r e s  found f r o a  3.7 to 5 microns. 
- 
NATURAL XIR’ERALS 
The r e f l e c t i v i t y  of Rosamond Dry Lake i n  C a l i f o r n i a  and t h e  
Pawnee Grassland area i n  Colorado i s  o f  i n t e r e s t  s i n c e  t h e s e  areas 
are used f o r  comparison of r ad iomet r i c  measurements from satel l i tes  w i t h  
known s u r f a c e  cond i t ions .  
s o i l  froxi t h e s e  areas. The soil was taken from t h e  s u r f a c e  and 
preserved i n  i t s  o r i g i n a l  form as w e l l  e s  p o s s i b l e .  
show f e a t u r e s  due t o  water of hydrat ion near  1.4, 1.9 and 2.9 microns. 
F igu res  8 and 9 show<, t h e  r e f l e c t i v i t i e s  of 
Borh s a n p l e s  
S ince  m o s t  n a t u r a l  s u r f a c e  mine ra l s  are hydrated t h e s e  f e a t u r e s  w i l l .  
be  found i n  t h e i r  r e f l e c t i o n  spectrum. 
The Rosamond Pry  Lake s o i l  has f e a t u r e s  a t  3.96  and 3.48 microns 
due t o  ca rbona te s ,  mainly calcium carbonate.  
microns found i n  pure calcium carbonate  is r.ot seen and r a y  b e  
obscured by features such as t hose  seen i n  s i l i c a  sand due t o  q u a r t z  
i n  t h e  s o i l .  The Pawr.ee Grassland s o i l  shows t h e  ca rbona te  f e a t u r e  
a t  3.96 microns weakly and t h e  q u a r t z  f e a t u r e s  from 4.4 t o  4.8 microns. 
Gypsum i s  coinmon i n  much o f  t he  s o i l  of Western United S t a t e s  
The f e a t u r e  a t  4.68 
p a r t i c u l a r l y  i n  t h e  sand of t h e  White Sands Na t iona l  Monument. 
F i g u r e  10 shows t h e  r e f l e c t i v i t y  of a sample o f  t h i s  sand i n  i t s  
n a t u r a l  s ta te  and p a r t i a l l y  dehydrated t o  enhance t h e  f e a t u r e s .  
Agreement i s  good between tne sand f e a t u r e s  ana t h o s o f  calciurn s u l f a t e .  
Beach sand from ocean beaches is  l a r g e l y  s i l i c a  and t h e  sands from 
A t l a n t i c  C i t y ,  N. J .  and Daytona Beach, F l a .  whose r e f l e c t i v i t i e s  are 
shown i n  Figs. 11 and 12 e x h i b i t  t h e  f e a t u r e s  seen  i n  t h e  p u r e r  s i l ica 
sand. The Daytorxi beach sand was s i z e d  by s i e v e s  i n t o  t w o  p a r t s  one 
as shown i n  FLg. 12. 
The r e f l e c t i v i t y  of a sample of t h e  S a l t  Pool of Death Va l l ey ,  C a l i f .  
i s  shown i n  F igure  13.1 T h i s  sa l t  occur s  i n  cakes  w i t h  a rough, g r a n u l a r  
s u r f a c e  and t h e  cakes  were preserved i n t a c t  d u r i n g  measurement. The 
roughness  of t h e  s u r f a c e  and i m p u r i t i e s  p r e s e n t  accounr  for t h e  
g e n e r a l l y  lower r e f l e c t i v i t y  thaii t h a t  of pure  sodium c h l o r i d e .  
F igure  1G s b w s  t h e  reflectivity of  TWO ssinples of n i t r a t e  soi l  
3’ from Chi le .  Tne s o i i  from P~zmpa Sebraska  i s  approxlmateiy 15% SaKO 
15% NaCI and 5% S a g O 4 .  Tha; from O f i c i n a  Victoria is 20 t o  12% N a N 0 3  
w i t h  some N a C l  2nd Na,$O4. 
carbmate f e a t u r e  ove f l l app ing  one of t h e  n i t r a t e  f e a t u r e s .  
T h i s  -Pampa Nebraska specimen shows a s tong  
The 
O f i c i n a ,  Victoria specirnen shows a s t r o n g  f e a t u r e  a t  4.12 microns 
probably .due  t o  W03. 4 
DXSCUSSION: 
The i n f r a r e d  r e f l e c t i v i t i e s  of a number of cormon mine ra l s  
have s t r o n g  s p e c t r a l  f e a t u r e s .  Tnese f e a t u r e s  could  be used f o r  
remote i d e n t i f i c a t i o n  of minera ls  on t h e  s u r f a c e s  of t h e  moon o r  o t h e r  
p l a n e t s ,  whose s u r f a c e  i s  a c c e s s i b l e  to  i n f r a r e d .  These f e a t u r e s  
may also b e  a s e r i o u s  complicat ion i n  t h e  i n t e r p r e t a t i o n  o f  low 
r e s o l u t i o n  i n f r a r e d  s p e c t r a  of p l ane t s  with a n  atmosphere,  such as 
Xars s i n c e  they ,  i n  may cases, over lap  a b s o r p t i o n  f e a t u r e s  of v a r i o u s  
coimon atmospheric  gases .  
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SLnc2 r e s i r a k l e n  o r  r e s i h a l  r a y  f e a a i r e s  t h a t  would be s e e ~  i n  
i n  i n t e n s i t y  by dec reas ing  p a r t i c l e  s i z e  a d u s t y  s c r f a c e  such as n i g h t  
he expected a n  Kars or t h e  l u n a r  su r face  might be b e t t e r  be examined for 
minera l  c o n s t i t u e n t s  by r e f l e c t e d  r e t h e r  t han  emi t t ed  r a d i a t i o n .  A s  shown 
i n  a prev ious  work, (Hovis ( 4 ) )  on r e f l e c t i v i t y  of i r o n  ox ides ,  
r e f l e c t i o n  f e a t u r e s  are enhanced by reduced p a r t i c l e  s i z e .  
The large niLcSer o f  i no rgan ic  f e a t u r e s  p ~ s s i b i e  from z i n e r a l s  w i l l  
s e r i o u s l y  c o c p l i c a t e  d e t e c t i o n  of o rgaz ic  z a t e r L a l  by i e ~ 0 ~ 2  spec t rosco? ic  
i n v e s t i g a t i o n .  Tt woiild be d i f f i c u l :  t o  i d e n t i f y  any p a r t i c a l a r  s p e c t r a l  
f e a t u r e . s e e n  i n  reflecred spectra as positively organ ic  i n  o r i g i n  
when such  a l a r g e  number of ino rgan ic  f e a t u r e s  e x i s t .  
(To be sed for ctussifying ail NASA publications, journal articles, and other papen 
for inclusion in the Goddard Jwml.) 
. Part A - Space Sciences 
A 1. 
A 2. 
A 3. 
A 4. 
A 5. 
A 6. 
A 7. 
A 8. 
Astronomy and Astrophysics 
Celestial Mechanics and Geodesy 
Solar Physics 
Ionosphere and Radio Physics 
Fields and Particles 
Planetology 
Planetary Atmospheres 
General (subiects not clearfy belonging in any 
of categories 1-7) 
Part B - Space Technology 
B 1. Projects and Programs 
B 2. Space Dynamics and Control Systems 
B 3. Spacecmft and Subsystems 
B 4. Vehicle Technology 
B 6. Sensors 
B 7. General Electronics 
B 8. Environmental Testing 
B 9. Tracking Systems 
< 
- r l  B 5. & d i n g  Rockets i -  
B 10. General (subjects not clearly belonging in any 
of categories 1-9) 
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1 
I wouid l i k e  to acknowledge t h e  L n l i - i t e a  cooperation of 
H. Keegan and. V. Weidner of t h e  Kat iona l  Bureau of S tanda rds  i n  
all  of t h e  measurements from 2.5 t o  6 microns.  Var ious  specimens 
were p r o v i d e j  by i;. Er;ckss,:i of 3 . S . G . S .  zzd Hr. R-nbert Goldberg. 
Fig.  ; j  
Fig. 2 )  
Fig, 3 )  
Fig. 4) 
Fig. 5 )  
Fig. 6) 
Fig. 7) 
Fig. 61 
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Fig. 9) 
Fig. 103 
Fig.11) 
Fig. 12) 
Figi13) 
Fig.141 
Xefiectivizy of C G ~ C ~ G Z  Czrh:are 
Reflectivity of Sodium Carbonate 
Reflectivity of Hydrous Calcium Sulfate 
Reflectivity of Sodium Nitrate 
Ref1 ectivity of Potassium Nitrate 
Reflectivity of Sodium Chloride 
Reflectivity of Silica Sand 
3ef:ectivity of Rosanond Dry Lake Soil 
Reflectivity of Pewnee Grassland Soil 
Reflectivity of Gypsum S a d  
Reflectivity of Atlantic City, N . J .  Beach Sand'  
Reflectivity of Daytona Beach, Fla. Beach Sand 
Reflectivity of Salt Pool, Death Valley 
Reflectiviry of Chilean Nitrate Soil 
. . ..- . - .. . . .  
(1) D = r z ~ l d  E. ?";,cCarthy, Applied Optics: 4: 507 (1965) 
( 2 )  D. G. Rea, T. Belsky and M. Calvin, Science, 141, 923 (1963) 
(31 John U. White, J.O.S.A. ,  54,  1332 (1965) 
( 4 )  W. A .  Eovis, Icarus, in press 
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Infrared Reflectivity of Some Common Minerals

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