Morphological Identification of Rocks around Ranupani Village, Mount Semeru, Lumajang, East Java

Mount Semeru is the highest volcano on Java Island, with its peak of Mahameru at 3.676 meters above sea level (masl). The Semeru volcano is of the Strato type with volcanic-strombolian eruption. This study aims to identify the morphology of rocks found around the mountain in Ranupani Village, Mount Semeru, Lumajang, East Java. Samples were prepared from rocks that had been searched in a limited area from Ranupani Village, Semeru Volcano, then selected, and taken a small portion of the process into powder form, then filtered or sifted. After the sieving process is done, a subtle powder will be obtained. The subtle powder is then ready for XRD testing to find out the identification of the rock morphology. The x-ray diffraction test results were then analyzed qualitatively with the method of search and match. Qualitative analysis of XRD is to determine the crystal structure and composition of the elements contained in these rocks. The sample, phase 1, showed the presence of Barium diiron tetraoxide (Ba Fe2 O4) to form a crystal system orthorhombic. The sample_2 phase shows the presence of Albite (Al Na O8 Si3) to form a crystal system triclinic (anorthic). In sample_3, the phase indicates the presence of Anorthite (Al2 Ca O8 Si2) and the presence of Albite (Al Na O8 Si3) to form a crystal system triclinic (anorthic). The results of rock characteristics with X-ray diffraction show that in sample _2 and sample _3, resulting Silica and Aluminum elements are present. This suggests that the predominant minerals in these samples are likely silicates, such as feldspars and clay minerals, which are rich in silica and aluminum. Further analysis is needed to identify these samples’ specific mineral compositions and proportions. Through Match! 2, from the top of the diffraction pattern (short angle 2 10, 10-60 °), the sample corresponds to the silica and aluminum diffraction patterns.


Introduction 1.Structural Geology
Mount Semeru is the highest volcano in Java, Indonesia, with its peak Mahameru reaching 3.676 meters above sea level (masl).Semeru volcano is classified as a stratovolcano with a volcanic eruption type of Vulcanian-strombolian.Currently, the field of geological science plays an increasingly vital role within the community, particularly in providing information about the region's evolving geological conditions and activities.The progression and advancement of this scientific discipline are driving the initiation of regional research efforts; however, a more comprehensive investigation is still necessary to supplement the existing geological data.This includes encompassing the geomorphological conditions, stratigraphy, geological structures, and other applicable geological aspects.Structural geology, a subfield within the geological sciences, examines the rock architecture resulting from deformation processes.The study of geological structures encompasses various aspects, such as analyzing the crustal architecture or formation and understanding the relationships among rock layers currently found folded (exhibiting folds) and weathered at several kilometers above sea level [1][2][3].
There is a prevailing perspective that structural geology places a greater emphasis on examining geological structural elements, such as folding, fractures, faults, and the like, which are integral to tectonic units [4][5][6].On the other hand, tectonics and geotectonics are regarded as studies of a larger scale focused on geological entities such as sedimentary basins, mountain ranges, ocean floors, and the like [7][8][9].
Structural geology is highly essential across various domains.Generally, it plays a pivotal role in Earth exploration and the investigation of the layered Earth structure and the formation of geological structures within rock formations, particularly in relation to their origin and processes [10].Moreover, through the study of structural geology, insights can be gained into the processes governing the occurrence of geological resources like water, petroleum, natural gas, and other minerals [11].Understanding the types of rock structures present enables a better comprehension of the rock forms resulting from Earth's processes.In areas of active tectonics, the precise identification of geological structures becomes crucial for selecting safe locations for schools, hospitals, dams, bridges, and nuclear facilities.Comprehending structural geology also contributes significantly to understanding the challenges faced by Earth's natural resources, which undergo depletion.Analyzing rock formations makes it possible to decipher a given region's history.
The primary objective of this research is to comprehensively analyze and characterize the geological morphology of the rocks in the vicinity of Ranupani Village, near Mount Semeru in Lumajang, East Java.This study's findings will have significant implications for understanding the region's geological history, potential hazards, and land use planning.

Mount Semeru Geochemistry
Based on the chemical parameters proposed by Gill [12], the young rocks of Mount Semeru can be classified into basalts, basic andesites, and acidic andesites (46.5 to 60% SiO2).Dacitic rocks (66.6% SiO2) are only found in one old lava flow within the Ajek-ajek group.According to the Na2O + K2O, MgO, and FeO AFM diagram [13], the volcanic rocks of the Mount Semeru Complex are classified as calc-alkaline rocks.The low content of Mg-number (20.7-56.6 ppm), Ni (2-56 ppm), and Cr (1-160 ppm) in the rocks of the Mount Semeru Complex indicate that they do not originate from primary magma sources.Instead, these rocks have undergone secondary processes such as fractional crystallization, contamination, and/or magma mixing.

XRD
X-ray Diffraction (XRD) is an instrument to characterize crystal structures and crystal sizes in solid materials (Figure 1).When subjected to analysis via XRD, all materials containing specific crystals exhibit distinct and specific peaks [14,15].Hence, a limitation of this instrument lies in its inability to characterize amorphous materials.The primary components of XRD consist of the cathode ray tube (where X-rays are generated), sample holder, and detector.
XRD provides diffraction data and quantification of diffraction intensity at various angles for a given material.Data obtained from XRD include the diffracted X-ray intensity and corresponding 2 angles.Each peak present in an XRD pattern corresponds to a crystallographic plane with a specific orientation [16].The crystal irradiated by the X-ray beam constitutes the material (sample), resulting in a transmitted beam intensity lower than the incident beam intensity.Scattered X-ray beams exhibit both destructive interference and constructive interference effects.
When a material is exposed to X-rays, the transmitted beam intensity is lower than the incident beam intensity due to absorption by the material and scattering by the atoms within it.Scattered X-ray beams may either cancel each other out due to phase differences or reinforce each other due to matching phases.Strengthening X-ray beams (constructive interference) from the scattered wave is a diffraction phenomenon.X-rays incident on a crystal plane scatter in all directions; for constructive interference between scattered beams with different path differences to occur, they must fulfill the pattern of  [17].

Method 2.1. Rock selection
Rock samples were collected from various areas within Ranupani Village, Mount Semeru, in this study.These rock samples underwent a selection and refinement process to transform into powder form, which was subsequently prepared for X-ray Diffraction (XRD) testing.The schematic stages of this research are illustrated in Figure 2.

Sample preparation
The samples were meticulously sourced from a delimited area within Ranupani Village, Mount Semeru.After careful selection, a small portion of the rock was extracted and subjected to the comminution process, forming powdered material.After this, the material underwent a meticulous sieving procedure to achieve a finely granulated state.This finely granulated powder was then poised for the subsequent X-ray Diffraction (XRD) analysis, aimed at discerning the morphological characteristics of the rock.
The outcomes derived from the X-ray diffraction test were subjected to qualitative scrutiny by applying the search and match methodology.This qualitative XRD analysis was instrumental in elucidating the crystallographic structure and the elemental composition intrinsic to the rock sample.

Analysis X-ray Diffraction (XRD) testing stands as a crucial analytical technique capable of furnishing insights
into the mineral constituents present within a mining material, mainly rocks.XRD operates on the principle of X-ray diffraction, which is generated through the interaction with the crystalline structure of the examined material at specific angles.Typically, XRD is employed for quantity analysis that requires swift results without an exhaustive demand for precision.

Analysis
The results of the X-ray Diffraction (XRD) analysis conducted on the rock samples gathered from the vicinity of Ranupani Village, Mount Semeru, and tested at the XRD Laboratory of the ITS Research Center in Surabaya on December 17, 2018, are illustrated in Figure 3.The X-ray diffraction test was performed over an angular range of 10-90°.This testing stage primarily focused on the morphological identification of the samples.
The rock diffraction data are denoted by sample_1, sample_2, and sample_3.As observed in Figure 3a, the pattern corresponds to sample_1; Figure 3b displays the pattern for sample_2, while Figure 3c represents the pattern for sample_3.It has been identified that the phase present in sample_1 is Barium diiron tetraoxide.Furthermore, the phase found in sample_2 is Albite, whereas sample_3 contains both Anorthite and Albite phases.

Results of X-ray diffraction data search and match
The qualitative analysis of the X-ray diffraction data from the rock samples was conducted using Match! 2 software at the Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Surabaya.The morphological identification outcomes of the rock samples are presented as follows:

Sample_1
In sample_1, the phase reveals the presence of Barium diiron tetraoxide (BaFe2O4), forming an orthorhombic crystal system.The peak list is presented in Table 1.

Sample_2
In sample_2, the phase indicates the presence of Albite (AlNaO8Si3), forming a triclinic (anorthic) crystal system.The peak list is provided in Table 2.

Discussion
The results obtained from the X-ray diffraction (XRD) characterization of samples_2 and samples_3 provide valuable insights into the elemental composition of the rocks.The XRD analysis clearly indicates the presence of significant amounts of silicon and aluminum within these samples.This observation is further substantiated by the Match! 2 analysis, which demonstrates that the diffraction peak patterns, particularly within the short 2θ angle range of 10-60°, closely match the diffraction patterns associated with silicon and aluminum.These findings are consistent with previous research, as several studies have indicated that the silica sand from Mount Semeru exhibits high quality [18].This is supported by the chemical analysis results from Mount Semeru, which unequivocally confirm the prevalence of silicon and aluminum as the primary constituents within the volcanic rocks.The concurrence between the XRD characterization results presented in this study and the earlier chemical analyses not only serves to validate the precision and credibility of our research but also contributes significantly to advancing our comprehension of the geological composition of the rocks in the proximity of Mount Semeru.

Conclusion
Sample_1 indicates the presence of Barium diiron tetraoxide (BaFe2O4) forming an orthorhombic crystal system.Sample_2 reveals the existence of Albite (AlNaO8Si3) in a triclinic (anorthic) crystal system.Sample_3 exhibits the presence of Anorthite (Al2CaO8Si2) and Albite (AlNaO8Si3), both forming a triclinic (anorthic) crystal system.The X-ray diffraction (XRD) characterization of the rock samples reveals that samples_2 and samples_3 contain elements of Silicon and Aluminum.The Match! 2 analysis, based on the peak patterns of diffraction (in the short 2θ angle range of 10-60°), corresponds to the diffraction patterns of silicon and aluminum.This study is currently in the phase of morphological identification of rocks through XRD analysis.Further research can be expanded using X-ray Fluorescence (XRF) testing for a more comprehensive analysis.