Mica-rich rocks (shales, slates, schists) are a major and significant component of the continental crust. They are often characterized by a strong seismic anisotropy, a key factor in the seismic interpretation of the architecture of the continental crust. Roofing slates are a group of natural rocks used in construction that must possess a continuous and undeformed slaty cleavage. This makes roofing slates an exceptional benchmark to study the relation between the rock microstructure and the development of seismic anisotropy in single-foliated low-grade slates. Direct measurements of seismic velocities using an ultrasonic wavemeter at room conditions were done on eight cubic samples from active quarries in the NW Iberian Peninsula. Seismic velocities were also calculated using the Hill averaging method from crystallographic preferred orientation (CPO) maps of slate-forming minerals on the same sample blocks using electron backscatter diffraction (EBSD), achieving unprecedented coverages of up to 87%. The seismic velocities estimated by both methods are similar parallel to the slaty cleavage but much slower using direct measures in the axial direction, producing anisotropies for Vp and Vs1 up to 7 and 5 times higher than the calculated velocities. The results are indicative of the highly anisotropic contribution that cracks, pores and fractures have in single-foliated slates, given the strong shape fabric that the rocks present. The samples selected also show that not all slates exhibit near-transverse isotropy, as it has been commonly assumed.

云母丰富的岩石（页岩，板岩，片岩）是大陆壳的重要组成部分。它们通常具有强烈的地震各向异性，这是对大陆壳结构进行地震解释的关键因素。屋顶板岩是一组用于建筑的天然岩石，必须具有连续且未变形的板岩劈裂。这使得屋顶板岩成为研究岩石微结构与单叶低品位板岩地震各向异性发展之间关系的出色基准。使用超声波仪在室温下对西北伊比利亚半岛活跃采石场中的八个立方样品进行了地震速度的直接测量。还使用希尔平均法，使用电子背散射衍射（EBSD），根据同一样品块上形成板岩的矿物的晶体学优选取向（CPO）图，计算了地震速度，实现了前所未有的覆盖率达87％。两种方法估算的地震速度与板条分裂平行，但沿轴向直接测量要慢得多，对Vp和Vs1产生的各向异性要比计算速度高7到5倍。结果表明，考虑到岩石所具有的坚固形状，岩石，裂缝和裂纹在单叶板岩中具有很高的各向异性。所选择的样本还表明，并非所有板岩都表现出近乎横向的各向同性，正如通常所假设的那样。