Huygens Institute - Royal Netherlands Academy of Arts and Sciences (KNAW)
Citation:
H.A. Brouwer, On micaleusite basalt from Eastern Borneo, in:
KNAW, Proceedings, 12, 1909-1910, Amsterdam, 1910, pp. 148-154
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Petrography. - "On Micaleucite basalt jroJn Easte)'n B01'lWO." By
H. A. BROUWER. (Oommunicated by Prof. G. A. F. MOLENGRAAFF.)
The occurrence of leucite rocks in our Eást-Indian Archipelago,
at the same time the first occurrence outside Europe, was observed
by VOGELSANG fi'om the Gunung Bantal Susum on the island Bawean;
VOGELSANG'S observations were described aftel' his death by ZIRKEL 1)
in 1875.
LORIÉ 2) described Jeucite rocks from Java from the Gunung Ringgit,
an extinct volcal1o on the north coast of the residence Besuki, and
VERBEEK 3) from the Gunung Muria and the mountain Patti-Ajam
in the residency Djapara. BEHRENS 4) described rocks from the same
localities.
In Oelebes WICHMANN 6) discovered in 1888 leucite basalt in the
sonthwestern peninsuIa among lhe bonIders of the river Pangkad,jéné,
and leucitites from the rivers Masépé (nea1' the kampong of the same
name) and Walannaë, a tributa1'Y of the Mil1l'alang (upper course of
the Tjel1l'ana). RE'l'GERS B) mentions leucitites ti'om Malawa (Mountain
Regencies, northe1'n cTistrict, South Oelebes) and finally BÜOKING biotite
leucite basalt, underlying limestonc with Nummulites east of Kantisang
nea1' Bangkang Sakiang 7), leucite basalt nea1' TandjiÏlg Lossa on the
Mandar toast (lat. 2°42' south) and leucitites in conglomerates 11ea1'
the kampong Tambi in the bay of Manudju s).
From Borneo no leucite rocks were hithe1'to known.
Now Prof. MOLENGRAAFF recently discovel'ed among the collection
of rocks, made by PJ'of. NlEUWENHUIS in the basins of the Mahakam
and the Kajan in Eastern Borneo in the years 1896 -'97 and
1898-1900, a leucite rock, which he placed at my disposal fol'
furthel' investigation.
F. ZIRKEL, Neues Jahrbuch f. Mineral. 1875, blz. 175.
~) J. LO~IÉ, Bijdrage tot de kennis del' Javaansche El'Uptiefgesteenten. Dissel'tatioll.
p. 247. Utrecht, 1879.
3) R. D. M. VERBI:EK und R. FENNEMA, Neue Geologische Entdeckungen auf Java.
NE'ues Jahrb. f. Mineral. BB. 2. 1883, p. 205.
4) H. BEHRENS, Beitl'äge zur Petl'ogl'aphie des Indischen Archipels. Il. Vel'h. K.
Ak. v. W. Amsterkam. XXXIII. 1883.
ij) A. WICmIANN, Leucitgesteine von der Insel Celebes. Petl'ogl'. Studien über den
Indischen Al'chipel. I. Natumk. Tijdschr. v. Ned. Indië. LIlI. 3. 1893.
0) J. RETGERS, Jaarb. v. h. Mijnw. in Ned. Oost-Indië, 1895, p. 99.
7) H. BÜCKING, Leucitbasalt aus der Gegend von Panc1kadjéné in Süd·Celebes.
Bel'. Naturf. Ges. Fl'eiburg i. B. 1899, XI, p. 99.
8) H. BÜCKING, Beiträge ZUl' Geologie von Oelebes. Sammlungell des GeoJogischE'n
Reichsmuseums in Leiden. VII. 1902-1904, p. 43.
1)
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lt was found on August 26 th 1900 in
11 boulder bed in the Up pel'Kajan above the mouth of the Laja 1) which is a small rivulet thel'e.
The dimensions of the boulder (14 X 8 X 8 cM.) indicate transport
over a not ver)' large distance; probably it was derived fi'om the
northern slope of the Bawoei Moumains which form the water shed
between the basins of the Upper-Mahakam and the Upper-Kajan.
A little further to the East, where NmuwENIIuIS cl'ossed this range,
it consists of steeply inclined strata of the oid slate formation of the
Uppel'-Kapoeas mountains, _which are overlaid unconformably by
horizon tal strata of sandstone.
Th is leucite rock ha,s the extern al appcarance of a lamprophyl':
numerous stl'ongly glitLering bron ze colonred flakes of mica (+3 mm.)
con trast with a very finely cl'YRtalline, but not absolntcly compact
matrix. On cal'eful inspectioll a Yery large number of olivine crystals
may be seen disseminated through the entire rock; only in exceptional cases do they reach a size of 2 mm.; they are mostly smaller
than 0,5 mmo allel are noticeable on account of their yellowish brown
colour allel strong lustre. 111 external appeara,nce the rock resembles
a minette.
.
Under the microscope the matrix is seen to consist of leucite, large
light green microlites of diopside and numerous smal! idiomol'phic
crystals of titanic iron ore. The leucite crystals (on the avel'age
0.05 m.m.) frequently show clearly octagonal and hexagona1 outlines,
others are ronneleel Ol' have irl'egular con tours ; angite microlites incluelecl in them are al'ranged more Ol' less concentrically with their
longer axis parallel to the circumference (fig. 4:). At a high magnification anel by the use of aselenite elise double l'efi'action anel
twinning laminae caIl be obsel'vecl. The diopsiele-microlites sometimes
have somewhat lurger elimensions anel then a,ppeaJ' as elongatecl
light green pleochl'oitic prisms witbout well definael terminal fhees;
they are sometimes twinned. The eliopsiele does not appeal' as rea1
phenocryst.
The olivine generally forms crystallogmphically well-defined crystals,
with welI mal'kecl cleavage acrol'dillg ia (010); ihe clcavnge arcoreling
to (001) onl,)" indiratecl by ill-defineel short cl'acks. The olivine has
not undol'gone the slightest altel'ation, is colonrless auel t.rau sparen t
anel generally free fi'om inrilIsions ; the larger cl'ystals only surrounel
sometimes a few small crystals of iron O1'e anel augite microlites.
The mica occurs in two ways, either strongly resorbeel- in which
case the are grains accllmulate in a zone just l'ound the crystal, Ol'
1)
A. W.
NIEUWENHUlS,
Quel' dUl'ch Borneo, lI, p. 350. Leiden. 1904.
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form a framework within the original crystal of mica arl'anged in
the three directions (fig. 3) - or not resorbed at all.
In the former case hal'dly any inclusioJls occur, in rhe latter case
the mica contains very many poïkihtically Ïlfcluded leucite crystaIs
and microlites of augite, and thus the mica is in th is case the last
product of crystallisation. The slightly birefringent sections aftel' the
basaI pinacoid are not defined crystallographically j they show in
convergent light the sharp bisectl'ix and optical axes diverging with
an angle wInch is unusual for biotite; sections aftel' undetermined
directions show twinning according Tschel'mak's law. The pIechroism
is btrong and abnormal:
a
>
>
pale orange red
canary yellow
light yellow to colourless.
fr om which it is evident that also the cleavage laminae are stl'ongIy
pleochroitic.
The resorbed crystals show, in these parts whirh have heen preserved, the same pleochroism; moreover a contimled gl'owth aftel'
the resorption period fi'equently Dccurs alld then the nucleus and the
periphel'Y are orientated in the same way (fig. 3).
The isolation of pure mica matel'ial was impossible on account of
the large am ou nt of incIusions, so that the chemical composition can
throw no fllrther light on the abnormal optical properties.
1'he chemical composition of the rock appeal's from the following
analyses (I) carried out by F. PrsANI and the authol'. For the sake
of comparison there are added the analyses of a few other rocks
which are closely allied mineralogically and chemically.
I. Mica leucitebasalt. Bouldel' Oeloe Kajan. B01'l1eo's OosterAfdeelülg Anal. F. PlSANl and H. A. BROUWER.
11. "Minette of Highwood type". Arrow Peak. Highwood l\Iountains. Montana. Anal. H. W. FOOTE cf. L. V. PIRSSON BULT,.
N°. 237 U. S. Geol. Survey. 1905, p. 142. (BaD 0..18;
Sl'O 0.25).
III. Missourite. Shonkin Stock. Shonkin Creek. Highwood lVIollntains. Mont. Anal. E. B. HURLBURT cf. L. V. PIRSSON Bur,T.
N°. 237 U. S. Geol. Survey. 1905 p. 115.
IV. Analcim~ basalt. The Basin. Cripple CI'eek Distr. Colorado.
Anal. W. F. HJLLEBRAND cf. CROSS JOURN. of Geol. Vol. V
1897 p. 689. (BaO 0.13; S1'O 0.12).
V. Leuciteabsal'okite. Ishawooa Canyon. Wyoming. Anal. J. E.
WHlTl'IELD
cf. A. HAGUE. Al\I. JOURN. ofScience Vol. XXXVIlI
,
July 1889.
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I
I
\"
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( 151 )
VI. Leuciteuasalt. Bongsbel'g 11ear Telm. Eifel. Anal. E. HUSSAK cf.
E. HUSSAK SITZ. Bel'. K. Akad. der Wiss. Wien Vol. 77 I. 1878.
VII. Biotiteleuritebasalt Pangkadjéné. Souih Celebes. Anal. Dr.
BRUHNS cf. H. BUCKING. Bel'. del' Naturf. Ges. zu Fl'eibul'g
i. n. XI 1899 p. 78.
III
II
IV
V
VI
/
SiOz
\46.04 I 4.6.04
46 06 14.5.59 I 47.28
1
44 35
.
VII
I
I 47 13
Ti02
2.20
0.64
0.73
1.22
o 88
Al 2 0s
12.40
12.23
10.01
12.98
11 56
FesO J
3 54
3.86
317
4.97
3.52
FeO
5.58
4.60
5.61
4.70
5.71
MnO
sp.
sp.
sp.
0.14
o 13
MgO
12.60
1038
14.74
8.36
13 17
12.31
4.16
CaO
8 38
8.97
10.55
11 09
9 20
11.47
9.00
Na~O
1.62
2.42
1.31
4..53
273
3.37
o 81
KsO
4. 87
5.77
5.14.
1.04.
2.17
1/.42
8.00
H20
• 3.5'1 1 )
2.87
i 44
3.91
2 96
o 59
0.18
P~05
1.14
SOs
sp.
0.05
o 91
o 03
0.11
D.03
U.05
Cl
tr.
10.20
14.47
t13 . 5O 113 .56
204..
I
Tota-;-I 100. 78 1 99 76 1 99.57 1 09 87 1100.08199 G2 1 JOO 07
InDlNGS 2) alroady mentions the intel'mediate place, which the chemical
composition of biotite occupies between that of olivine and felspar i
the biotite molecule can be split into olivine and the oxide molecules
necessary for the fOl'mation of felspal' or felspatoids. It follows
from this, in conjunction with the analyses quoted abm'e, that in
rocks of certain chemical composition where the proportions are
favourable to the genesis of thp,se mineraIs, the latter may show a
large difference in relative propol'tions, whilst the conditions of crystallisation are but slightly different. Secondary biotite ma)" be readily
formed in these and in closely related rocks.
1) Loss on ignition.
~) J. P. InDlNGs. 'l'he origin of igneous rocks. Bull. Phil. Soc. Washington. Vol.
XII 1892. p. 166.
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I
I
'
A leucite basalt, l'ich in magnesium, is the type from Bongsbel'g near
Pelm in the Eitel (VI), which contains mnch olivine whel'eas the
fOl'ming of biotite shows a certain relation to that of the olivine
crystaJs, for the former are only fonnd deposited round the latter ;
the complete freshness of both minerals makes an altel'ation' of one
into the other iropl'obable; a simultaneous Ol'igin is indicated.
On comparison wüh the "Minette of Highwood type" or "mica
basalt" of the Highwood MOllntains (H) we see that here the pl'opol'tion
of alkalies to silica by all equal content of Al2 0 3 wonld have been
in itself more favourable lor the formation of leucite, whel'eas this
mineral only occurs Ü1 a subordinate proportion in the matrix on ille
side of alkali felspal'. This minette conta.ins but little olivine ancl n,lso
has augite among its phenocl'ysts. The biotite OCCUl'S as weIl in the
matrix as also as phenocrysts, alld in the latter case the slightly
pleochl'oitic paJe, yellowish brown cl'ystals are surrounded by a dal'k
border of l11uch stronger pleoch1'oism, corresponding with that of the
biotite of the matrix. In this case also the1'e are therefo1'e two distinct
periods of mica f01'l11ation, the first being intratelluric followed by
l'esorption, the11 resumed gl'oWLh of the older crystals and crystallisation of the matrix, in this rock howevel' nncler different conditions,
so that the biotite crystals cOllId not attain large dimensions.
With the in verse proportion of aJkalies and a hig'h water content
rhe conditions, when rapid cooIing undel' pressure takes pI ace, are
favol.ll'able for the formation of analcime uasalt or monchiquite; the
large 10ss 011 ignition of t11e mineral here described makes the presence of analcime in the matrix very probable.
In the biotite leucite basalt (VII), containing but Iittle MgO, which
was descl'ibecl by BÜCKING ü:om South Celebes the biotite occurs as
l'esol'bed phenocl'ysts and here also a second genel'tl,tion of s111a11
crystals oC'Ctll'S in the matrix; the cl'ystallographically wel! cloiiued
phenocrysts of olivine have been altered completely into calcite ünd
serpentine. In this case too the lencite is only found in the matrix;
the largel' crystals (0.1 m.m.) show feebJe birefringence l1nd vague twinning laminae. The apatitc, which OCCUl'S here in fairly largc qnn,l1tÎties,
is entil'ely ,absent in our rock. All the other Easl Indian Jeucilc rocks
are pOOl' in biotite (WICmfANN on1y mentions it in the intas of ths
Peak of Maros) and in most of them leucite is not limited to the
matrix (Djapara).
Chemically the rock here described is distinguished from most
other leucite bas~),Hs by its lampl'ophYl'ic chal'actel'. As in the case
of the lamprophyric effusive rninerals, separaLed into a distinct gl'OUp
by ROSENBuscrr anel in which fol' instanee the phlogopiif3 bearing
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leucite rocks of the· Leucite HiIls at'e elassified (Wyomingite etc.),
the present rock is characteriz~el by a small AI 2 0 3 contenl, a large
proportion of oxydes of bivalent me(als, and the pl'eponderance of
magnesia over lime, propel·ties which tllese rocks have in common
with the lamprophyric dyke rocks.
Since the Ol'igin of mica seems to be connected with pressure
and pneumatolysis, so tlmt for this 1'eason alreacly it is rare in tlte
matrix of effusive roeks, it woulcl appeal' that the OCClllTence in
lal'gè crY$.tals as the last pl:oduct of &olidification would exclude a
character as effllsive rock. That the OCClll'l'enee of lencite formation
is not confined to effusive magmas of definite chemical composition
is p1'oved e.g. by its presence in the intrusion ofmissourite 1), which
is a coarse granulal' rock consisting of ,leucite, diopside and oliyine
with iron ore and apatite. On comparing the analyses I anel III
we see how much chemical and mineralogical composition are
aIlied; the missoul'ite is the deep seated modification of the rock
here described.
HÖGBOl\[ 2) gescl'ibes a gl'owing together of leucite and mica ü'om
Frascati in whieh tlle latter encloses in strongly glittel'ing bl'onzecoloured cl'ystals several e.m. long, pselldomorphs of leucite which are
up to 5 c.m. in length; th is is explained by a suelelen Ol'igin of the
lal'ge mica ineliyidllals, which then encloseel the al ready crystaIlizeel
lencites pOÏkilitieally. The complete fl'eshness of the poïkiliticalleucite
in Ollr rock is pecllliar in connection with the instability 3) of this
lIlineral anel the conditions of ol'igin of the mica.
Fl'OIIl all that has been saiel above it follows, tbat the matrix of
the rock here describeel was very probably crystallized very rapidly
and under pl'essure, eonditions which are l'ealized in dykes anel
smaH intrusions. Among the lampl'ophyric dyke rocks our rock is
alliecl to the monchiquites anel is distinguisheel from the minettes not
only by the complete absence of felspal' but a]so by the high content
of iron ore anel the nature of the femic constituents.
At any rate, as long as the geological eharactel' of this rock is not
e1etel'mineel, it must be run geel into a group with wbieh it agrees
in qualitative minel'alogical composition ; the complete absenee of
1) WALTHER H. WEED and L. V. PIRSSON, Missoul'Ïte, a new leucite rock fl'om
the Highwood Monntains, Montana. Amer. Journ. of Science 1896, 1I, p. 315.
~) A. G. HÖGJ30M. Ubel' einige Milleralverwachsungen. S. Verwachsung von
Leucit und Glimmer. Bull. Qeol. Inslitulion of th!:' Ulliversity of Upsala. Vol ITI,
p. 450. 1896-1897,
3) A. LACROIX, Elude minél'alogiquc des produih;, silicatés dr l'Ól'UpliCill du Vésuve
(Avl'il 1906). Paris 19')7. p. 96.
11
J?roceedings Royal Acad. Amsterdam. Vol. XII.
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I
felspar as weU as the abunclance of mica and olivine is sufficientlj
expl'~ssed in the name micaleucite basalt.
It is left· to furthel' explol'ations of this interesting tel'ritOl:Y, t9 mak~
out to what extent the above me~t.ioned suggestions are correct, and
whether this rock beJong:s to a group of lamprophYl'ic dyke rocks,
of which the transitions to minettes and monchiquites are known
in their leucite bearing varieties.
EXPLANATION OF FIGURES:
Above, a phenocryst of olivine; below aresorbed ci-ystal of mica and -to
the left of this non·resorbed mica in the position of greatest absorption
with well·defined cleavage lines. The matrix consists of lellcite, augite
microlites and ore.
Fig. 2. ~'rom the top somewhat to the left to the bottom somewhat lo the right
tbe dark band consists of non-resorbed mica; the poïkilitical character with
regar:d to leucite and diopside microlites is dear ..The olivine encloses a
few ore granu'es and augite miérolites.
l"ig. 3. Resorbed mica, surroundéd by a border of similarly orientated non resorbed
mica (continued growtb of the crystaJs. afler the resorption period).
Fig_ 4. Leucite crystaJs with inclusions, poïkililically surrounded by non-resorbed
mica.
Fig. 1.
Chemistry. - "On tlw mclioactivitp of .Rubidium compouncls."
By Dr. E. H. BÜCHNER. (Uommunicated by Prof. A. F.HoUElIIAN).
Althollgh the expel'iments to be descl'ibed are üU' from completed,
I think it all the same desirabie to make a pro vision al communi('ation as to the results al ready obtained, in view of the long' time
these kinds of experiments l'equire.
CAMPBELL 1) discovered about two years ago that potassium salts,
although . but very feebly so in comparison with uranium 'and the
other . radioactive salts, emit l'ays which ionise the aü' anel so cause.
the discharge of an electroscope. This discovel'y was confil'med from
val'ious quarters and LEVIN and RUER 2) succeeded in obsel'ving' the
action of potassium salts on th~ photographic plate. It 8eems, thel'efore, to be pretty certain that -potassium salts are eitbel' l'adioactive'
themselves, Ol' àre always conta,minated with a radioactive sllbstance;
but as it has been proved that this impurity cannot be one of the
lmown active substances it is natm'al to assume the exisfence of an'
active alkali metal, which should always exist in traces in }Jotassium
salts. In Ol'der to gradually solve this question, it seerned l in the
1) Le Radium Iy, 199,
2) Phys, Zeilschr. 9, 24.8,
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H. A. BROUWER. -Micaleucite basalt of Eastern Borneo."
Fig. 1.
Fig. 2.
50 X
50
X
Fig. 3.
Fig. 4.
50 X
500 X
Procecdings Royal Acad. Amsterdam. Vol. XIl.
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