SPECIMEN ID
024-SiO₂
MATERIAL CLASS
Crystalline Mineral
STATUS
Under Evaluation
DOMAIN
Optical Materials
Analysis
Specimen 024-SiO₂ Incident
The specimen transmits incident visible light with high clarity across the full visible range and into the near-ultraviolet. Mild birefringence is detectable under polarized light examination, significantly lower in magnitude than Specimen 023-CaCO₃ but sufficient to confirm anisotropic optical behavior. Prismatic surface faces produce weak specular reflections consistent with a polished single-crystal face.
Specimen 024-SiO₂ Structure
Hexagonal prismatic crystal habit with pyramidal terminations observed. Characteristic conchoidal fracture surfaces present on non-cleaved faces. The trigonal crystal system produces a helical SiO₂ lattice arrangement which confers chirality — the specimen exhibits optical activity, rotating the plane of polarized light along the optical axis direction. Handedness (left or right) to be confirmed.
Specimen 024-SiO₂ Spectral
Broad optical transmission window confirmed from approximately 150 nm (UV) through 4 μm (mid-infrared), making this specimen optically functional well beyond the visible range. No significant absorption bands in visible or near-IR. The piezoelectric lattice generates measurable charge displacement under mechanical stress, indicating an active electromechanical response that distinguishes this specimen from purely passive optical materials in the series.
Profile
Overview
Specimen 024-SiO₂ is a crystalline quartz sample — silicon dioxide in its stable low-temperature alpha-quartz phase. Unlike the preceding amorphous or polycrystalline silica forms, this specimen presents a well-formed single-crystal structure with measurable piezoelectric and optical rotation properties arising directly from its non-centrosymmetric lattice arrangement.
The specimen is the first piezoelectrically active entry in the Optical Materials intake series. Origin undisclosed. Crystal habit and face development suggest natural growth or controlled hydrothermal synthesis. No surface coatings or treatments detected. Currently held under passive optical and electromechanical evaluation pending full characterization and phase confirmation.
Properties
Alpha-quartz belongs to the trigonal crystal system (space group P3₁21 or P3₂21 depending on handedness) and lacks a center of inversion symmetry, producing piezoelectricity along specific crystallographic axes. Mechanical compression along the X-axis generates a proportional electric potential across opposing faces — the direct piezoelectric effect. Conversely, an applied field produces dimensional change, the converse effect.
Optical properties include weak birefringence (Δn ≈ 0.009 at 589 nm), optical rotation of approximately 21.7°/mm for light traveling along the c-axis, and a refractive index of approximately 1.544 (ordinary) and 1.553 (extraordinary). The wide transmission window — from deep UV to mid-IR — makes it functionally useful as an optical window material far beyond the visible band. Phase stability under ambient conditions is high; the alpha-to-beta transition occurs at 573°C and is fully reversible.
Classification
Specimen 024-SiO₂ is classified under Optical Materials — Crystalline Minerals / Piezoelectric. Material identity as alpha-quartz (silicon dioxide, trigonal, P3₁21/P3₂21) is provisionally confirmed based on crystal morphology, optical rotation detection, birefringence magnitude, and transmission profile. Chirality handedness remains to be determined by polarimetric measurement.
Recommended follow-up includes: X-ray diffraction for lattice parameter confirmation and space group determination; polarimetric measurement to assign left or right handedness; piezoelectric coefficient (d₁₁) measurement along the X-axis under calibrated load; and transmission spectroscopy from 150 nm to 4 μm for full window characterization. Specimen is a strong candidate for the Archive’s electromechanical optical reference collection upon classification completion.